Colorectal cancer (CRC) involves the uncontrolled proliferation of glandular epithelial cells in the colon or rectum. The high mortality rate associated with CRC has driven extensive research into innovative diagnostic and therapeutic strategies. Among these, microRNAs (miRNA) have gained attention for their crucial role in regulating various cellular processes that contribute to the initiation, progression, and metastasis of CRC.

This systematic review aimed to assess the roles of various miRNAs in CRC by analyzing multiple studies. The PICO framework was followed to structure the study regarding miRNA involved in CRC development and progression compared to normal cases. The outcomes were measured according miRNAs impact on CRC progression, survival rates, and treatment response. Systematic review of studies published from 2000 to November 2023 were included. Data were collected from prominent databases, including Google Scholar, PubMed, ScienceDirect, Irandoc, SID, and Magiran, covering studies from 2000 to November 2023. Studies were managed using EndNote for citation management, and duplicates were removed. The remaining studies were evaluated based on predefined inclusion and exclusion criteria.

In our review, we categorized 28 miRNAs based on their potential tumor suppressor or oncogenic effects in CRC progression. Among them, 14 miRNAs were highlighted as important based on the assessment using TCGA data, with miR-200a also showing a significant effect on patient survival.

This study compiled and analyzed validated miRNAs associated with CRC progression. The findings suggest the potential of these miRNAs as non-invasive biomarkers, which may be used alone or in combination with traditional tumor markers for improved diagnostic and prognostic applications in CRC. This review contributes novel insights by updating the current understanding and offering a comprehensive evaluation of miRNAs in CRC.

Early-onset colorectal cancer (EOCRC) shows a different epidemiological trend compared to later-onset colorectal cancer, with its incidence rising in most regions and countries worldwide. However, the reasons behind this trend remain unclear. The etiology of EOCRC is complex and could involve both genetic and environmental factors. Apart from Lynch syndrome and Familial Adenomatous Polyposis, sporadic EOCRC exhibits a broad spectrum of pathogenic germline mutations, genetic polymorphisms, methylation changes, and chromosomal instability. Early-life exposures and environmental risk factors, including lifestyle and dietary risk factors, have been found to be associated with EOCRC risk. Meanwhile, specific chronic diseases, such as inflammatory bowel disease, diabetes, and metabolic syndrome, have been associated with EOCRC. Interactions between genetic and environmental risk factors in EOCRC have also been explored. Here we present findings from a narrative review of epidemiological studies on the assessment of early-life exposures, of EOCRC-specific environmental factors, and their interactions with susceptible loci. We also present results from EOCRC-specific genome-wide association studies that could be used to perform Mendelian randomization analyses to ascertain potential causal links between environmental factors and EOCRC.

FOLFIRI, a combination of folinic acid, 5-fluorouracil, and irinotecan, is one of the recommended first-line chemotherapeutic treatments for metastatic colorectal cancer. Unfortunately, acquired FOLFIRI resistance represents a common obstacle in the treatment of metastatic colorectal cancer patients. Thus, we aimed to identify mechanisms, gene alterations, and gene expression signatures contributing to acquired FOLFIRI resistance by mimicking this problem in a cell culture model and subsequent translation in clinical data sets. Three FOLFIRI-resistant colorectal cancer (CRC) cell lines were established by continuous FOLFIRI treatment. Comparative mutation screening (161 genes) and transcriptomics (pathway and differential expression analyses) were performed in parental and resistant cells. Data reconciliation was performed in GSE62322, a clinical FOLFIRI responder data set (intrinsic resistance). Relapse-free survival (RFS) associations of identified differentially expressed genes and potential gene signatures were investigated in 8 clinical CRC data sets. No mutual genetic alterations were found in FOLFIRI-resistant derivatives. Resistant cell lines displayed activation of mitogen-activated protein kinase, immune response, and epithelial-mesenchymal transition pathways. Twelve differentially expressed genes, significantly differentially expressed in at least 2 of the 3 resistant cell lines, were identified. Comparison with GSE62322 and subsequent survival analyses revealed a 5-gene FOLFIRI signature comprised of CAV2, TNC, TACSTD2, SERPINE2, and PERP that was associated with RFS in multiple data sets including the cancer genome atlas CRC (hazard ratio [HR] =2.634, P = 4.53 × 10-6), in pooled samples of all data sets (all stages [N = 1981]: HR = 1.852, P = 6.44 × 10-13; stage IV [N = 260]: HR = 2.462, P = 5.22 × 10-9). A multivariate Cox regression analysis identified the 5-gene signature as an independent prognostic factor in the cancer genome atlas data set (HR = 1.89, P = .0202). Our analyses revealed a 5-gene FOLFIRI resistance signature associated with RFS that may help predict FOLFIRI resistance and thus avoid unnecessary ineffective treatment. Signature members might also represent targets to fight FOLFIRI resistance.

Early-onset colorectal cancer (EO-CRC), characterized by diagnosis before the age of 50 years, has emerged as a significant healthcare challenge with increasing global incidence. While traditional risk factors such as family history and inherited syndromes contribute to EO-CRC, a substantial proportion of cases remain sporadic, necessitating further investigation into additional etiological factors. Molecular studies reveal heterogeneity in EO-CRC, with distinct mutational profiles compared to late-onset CRC. Clinical management presents unique considerations, including challenges in early detection and treatment strategies tailored to younger patients. Addressing EO-CRC requires a multidisciplinary approach integrating epidemiological, molecular, and clinical insights to improve prevention, diagnosis, and therapeutic outcomes. Emerging research avenues explore novel biomarkers and therapeutic targets, offering promise for advancing understanding and management of this disease in contemporary oncology practice.

This study aims to develop online calculators using machine learning models to predict survival probabilities for early- and late-onset colorectal cancer (EOCRC and LOCRC) over a 1- to 8-year period. We extracted data on 117,965 CRC patients from the published database spanning 2010 to 2021, divided into training and internal testing datasets. The data of 200 CRC patients from Chongqing Hospital of Jiangsu Province Hospital was used as the external testing dataset. We conducted univariate and multivariate regression analyses on the training dataset to identify key survival factors and develop predictive machine learning models. The models were evaluated using internal and external testing datasets based on AUC, accuracy, precision, recall, and F1 score. Web-based calculators were subsequently developed to predict survival curves for EOCRC and LOCRC patients under different treatment strategies. In the multivariate Cox regression analysis, 16 and 18 variables were independently significant survival factors for EOCRC and LOCRC, respectively. In the EOCRC group, the machine learning models achieved AUC values of 0.880 and 0.804 in the internal and external testing cohorts. For the LOCRC group, the machine learning models exhibited AUC values of 0.857 and 0.823 in the internal and external testing cohorts. The online calculators, powered by trained machine learning models, are accessible at https://eocrc-surv.streamlit.app/ and https://locrc-surv.streamlit.app/ . These tools estimate survival probabilities for EOCRC and LOCRC patients under various treatment strategies and display the corresponding survival curves post-treatment over the 1- to 8-year period. This study successfully developed online calculators using machine learning algorithms to predict 1- to 8-year survival probabilities for EOCRC and LOCRC patients under various treatment strategies.

Colorectal cancer (CRC) is the third-most common cancer globally and a leading cause of cancer-related deaths. While the prognostic and predictive roles of RAS mutations in advanced CRC are well-established, their significance in early-stage CRC remains a topic of debate. Studies have been conducted for many years on clinical and pathological parameters that may be associated with RAS mutation, and there are inconsistent results in this regard. Currently, the only biomarker used in early-stage CRC is microsatellite status. KRAS mutations are detected in 40-50% of patients with colorectal cancer. RAS activating mutations cause loss of EGFR regulation by acting on the RAS/RAF/MAPK signaling pathways. In advanced colorectal cancer, these mechanisms cause a decrease in the effectiveness of EGFR inhibitors. However, studies on patients with early-stage colorectal cancer have inconsistent results. This review highlights the prognostic and clinical significance of KRAS mutations in early-stage CRC, particularly in MSS tumors. In the MSS group, KRAS mutations were associated with shorter TTR and OS compared to DWT patients. In contrast, in the MSI-H group, KRAS mutations showed no prognostic effect in TTR and OS. However. KRAS mutations were associated with shorter SAR in both MSI-H and MSS groups of patients. The findings underscore the need for routine molecular profiling, including KRAS and MSI status, to refine risk stratification and guide adjuvant therapy decisions. Further studies are warranted to explore targeted therapeutic approaches for KRAS-mutant CRC in the adjuvant setting.

Reports indicate a worldwide increase in the incidence of Early-Onset Colorectal Carcinoma (EOCRC) (<50 years old). In an effort to understand the different modes of pathogenesis in early-onset CRC, colorectal tumors from EOCRC (<50 years old) and Late-Onset patients (LOCRC; >50 years old) were screened to eliminate microsatellite instability (MSI), nuclear β-catenin, and APC mutations, as these are known canonical factors in CRC pathogenesis. Small-RNA sequencing followed by comparative analysis revealed differential expression of 23 miRNAs (microRNAs) specific to EOCRC and 11 miRNAs specific to LOCRC. We validated the top 10 EOCRC DEMs in TCGA-COAD and TCGA-READ cohorts, followed by validation in additional EOCRC and LOCRC cohorts. Our integrated analysis revealed upregulation of hsa-miR-1247-3p and hsa-miR-148a-3p and downregulation of hsa-miR-326 between the two subsets. Experimentally validated targets of the above miRNAs were compared with differentially expressed genes in the TCGA dataset to identify targets with physiological significance in EOCRC development. Our analysis revealed metabolic reprogramming, downregulation of anoikis-regulating pathways, and changes in tissue morphogenesis, potentially leading to anchorage-independent growth and progression of epithelial-mesenchymal transition (EMT). Upregulated targets include proteins present in the basal part of intestinal epithelial cells and genes whose expression is known to correlate with invasion and poor prognosis.

Colorectal cancer (CRC) incidence and mortality before 50 have been rising alarmingly in the recent decades.

Using a cohort of 10,000 patients, this study investigates the clinical, mutational, and co-mutational features of CRC in early-onset (EOCRC, < 50 years) compared to late-onset (LOCRC, ≥ 50 years).

EOCRC was associated with a higher prevalence of Asian and Hispanic patients, rectal or left-sided tumors (72% vs. 59%), and advanced-stage disease. Molecular analyses revealed differences in mutation patterns, with EOCRC having higher frequencies of TP53 (74% vs. 68%, p < 0.01) and SMAD4 (17% vs. 14%, p = 0.015), while BRAF (5% vs. 11%, p < 0.001) and NOTCH1 (2.7% vs. 4.1%, p = 0.01) mutations were more prevalent in LOCRC. Stratification by tumor site and MSI status highlighted significant location- and age-specific molecular differences, such as increased KRAS and CTNNB1 mutations in right-sided EOCRC and higher BRAF prevalence in MSI-H LOCRC (47% vs. 6.7%, p < 0.001). Additionally, co-occurrence analysis revealed unique mutational networks in EOCRC MSS, including significant co-occurrences of FBXW7 with NOTCH3, RB1, and PIK3R1.

This study highlights the significance of age-specific molecular profiling, offering insights into the unique biology of EOCRC and potential clinical applications.

Despite a reduction of both incidence and mortality from CRC, recent studies have shown an increase in the incidence of early-onset CRC (EO-CRC). Data on this setting are limited. The aim of our study was to evaluate the clinical and molecular profiles of metastatic EO-CRC patients in order to identify differences compared to a late-onset CRC (LO-CRC) control group.

We retrospectively collected data from 1272 metastatic colorectal cancers from 5 different Italian Institutions. The main objective was to the evaluate clinical outcome for EO-CRC patients in comparison to patients included in the control group.

In the overall population, mOS was 34,7 in EO-CRC pts vs 43,0 months (mo) (p < 0,0001). In the RAS/BRAF mutated subgroup mOS in EO-CRC pts was 30,3 vs 34,0 mo (p = 0,0156). In RAS/BRAF wild-type EO-CRC mOS was 43,0 vs 50,0 mo (p = 0,0290). mPFS was 11,0 in EO-CRC pts vs 14,0 mo (p < 0,0001).

Findings indicate a general worse prognosis for patients with early-onset colorectal cancer compared to late-onset patients. Interestingly this seems to occur regardless of the molecular status. These observations might have a considerable impact on clinical practice and research.

The incidence of early-onset colorectal cancer (EOCRC) has been rising at an alarming rate in the USA, and EOCRC disproportionately affects racial/ethnic minorities. Here, we construct comprehensive profiles of EOCRC DNA methylomes at base-pair resolution for a cohort of Hispanic and African American patients.

We show the epigenetic landscape of these EOCRC patients differs from that of late-onset colorectal cancer patients, and methylation canyons in EOCRC tumor tissue preferentially overlapped genes in cancer-related pathways. Furthermore, we identify epigenetic alterations in metabolic genes that are specific to our racial/ethnic minority EOCRC cohort but not Caucasian patients from TCGA. Top genes differentially methylated between these cohorts included the obesity-protective MFAP2 gene as well as cancer risk susceptibility genes APOL3 and RNASEL.

In this study, we provide to the scientific community high-resolution DNA methylomes for a cohort of EOCRC patients from underrepresented populations. Our exploratory findings in this cohort highlight epigenetic mechanisms underlying the pathogenesis of EOCRC and nominate novel biomarkers for EOCRC in underrepresented populations.

The onset of colorectal cancer (CRC) in patients younger than 50 continues to rapidly increase. This study highlights the epidemiologic changes, risk factors, clinical characteristics, and molecular profiles prevalent in early onset CRC patients, and identifies key areas for future research. It has been noted that only a small fraction of early onset CRC cases is attributed to known hereditary mutations and fit the canonical pathway of late-onset colorectal cancer development. To highlight this, we review the genetic and epigenetic modifications specific to early onset CRC. We also discuss the synergetic effect of single-nucleotide polymorphisms and environmental factors on the early onset of CRC. Additionally, we discuss the potential of noninvasive biomarker assays to enhance early detection, screening, diagnosis, and prognostic outcome predictions.

Colorectal cancer (CRC) remains a significant health burden globally, necessitating a deeper understanding of its molecular landscape and prognostic markers. This study characterized ferroptosis-related genes (FRGs) to construct models for predicting overall survival (OS) across various CRC datasets.

In TCGA-COAD dataset, differentially expressed genes (DEGs) were identified between tumor and normal tissues using DESeq2 package. Prognostic genes were identified associated with OS, disease-specific survival, and progression-free interval using survival package. Additionally, FRGs were downloaded from FerrDb website, categorized into unclassified, marker, and driver genes. Finally, multiple models (Coxboost, Elastic Net, Gradient Boosting Machine, LASSO Regression, Partial Least Squares Regression for Cox Regression, Ridge Regression, Random Survival Forest [RSF], stepwise Cox Regression, Supervised Principal Components analysis, and Support Vector Machines) were employed to predict OS across multiple datasets (TCGA-COAD, GSE103479, GSE106584, GSE17536, GSE17537, GSE29621, GSE39084, GSE39582, and GSE72970) using intersection genes across DEGs, OS, disease-specific survival, and progression-free interval, and FRG categories.

Six intersection genes (ASNS, TIMP1, H19, CDKN2A, HOTAIR, and ASMTL-AS1) were identified, upregulated in tumor tissues, and associated with poor survival outcomes. In the TCGA-COAD dataset, the RSF model demonstrated the highest concordance index. Kaplan-Meier analysis revealed significantly lower OS probabilities in high-risk groups identified by the RSF model. The RSF model exhibited high accuracy with AUC values of 0.978, 0.985, and 0.965 for 1-, 3-, and 5-year survival predictions, respectively. Calibration curves demonstrated excellent agreement between predicted and observed survival probabilities. Decision curve analysis confirmed the clinical utility of the RSF model. Additionally, the model's performances were validated in GSE29621 dataset.

The study underscores the prognostic relevance of 6 intersection genes in CRC, providing insights into potential therapeutic targets and biomarkers for patient stratification. The RSF model demonstrates robust predictive performance, suggesting its utility in clinical risk assessment and personalized treatment strategies.

Tertiary lymphoid structures (TLSs) exert a crucial role in the tumor microenvironment (TME), impacting tumor development, immune escape, and drug resistance. Nonetheless, the heterogeneity of TLSs in colorectal cancer (CRC) and their impact on prognosis and treatment response remain unclear.

The authors collected genome, transcriptome, clinicopathological information, and digital pathology images from multiple sources. An unsupervised clustering algorithm was implemented to determine diverse TLS patterns in CRC based on the expression levels of 39 TLS signature genes (TSGs). Comprehensive explorations of heterogeneity encompassing mutation landscape, TME, biological characteristics, response to immunotherapy, and drug resistance were conducted using multiomics data. TLSscore was then developed to quantitatively assess TLS patterns of individuals for further clinical applicability.

Three distinct TLS patterns were identified in CRC. Cluster 1 exhibited upregulation of proliferation-related pathways, high metabolic activity, and intermediate prognosis, while Cluster 2 displayed activation of stromal and carcinogenic pathways and a worse prognosis. Both Cluster 1 and Cluster 2 may potentially benefit from adjuvant chemotherapy. Cluster 3, characterized by the activation of immune regulation and activation pathways, demonstrated a favorable prognosis and enhanced responsiveness to immunotherapy. The authors subsequently employed a regularization algorithm to construct the TLSscore based on nine core genes. Patients with lower TLSscore trended to prolonged prognosis and a more prominent presence of TLSs, which may benefit from immunotherapy. Conversely, those with higher TLSscore exhibited increased benefits from adjuvant chemotherapy.

The authors identified distinct TLS patterns in CRC and characterized their heterogeneity through multiomics analyses. The TLSscore held promise for guiding clinical decision-making and further advancing the field of personalized medicine in CRC.

Activated TGFβ signaling in the tumor microenvironment, which occurs independently of epithelial cancer cells, has emerged as a key driver of tumor progression in late-stage colorectal cancer (CRC). This study aimed to elucidate the contribution of TGFβ-activated stroma to serrated carcinogenesis, representing approximately 25% of CRCs and often characterized by oncogenic BRAF mutations. We used a transcriptional signature developed based on TGFβ-responsive, stroma-specific genes to infer TGFβ-dependent stromal activation and conducted in silico analyses in 3 single-cell RNA-seq datasets from a total of 39 CRC samples and 12 bulk transcriptomic datasets consisting of 2014 CRC and 416 precursor samples, of which 33 were serrated lesions. Single-cell analyses validated that the signature was expressed specifically by stromal cells, effectively excluding transcriptional signals derived from epithelial cells. We found that the signature was upregulated during malignant transformation and cancer progression, and it was particularly enriched in CRCs with mutant BRAF compared to wild-type counterparts. Furthermore, across four independent precursor datasets, serrated lesions exhibited significantly higher levels of TGFβ-responsive stromal activation compared to conventional adenomas. This large-scale analysis suggests that TGFβ-dependent stromal activation occurs early in serrated carcinogenesis. Our study provides novel insights into the molecular mechanisms underlying CRC development via the serrated pathway.

Although colorectal cancer (CRC) remains the second leading cause of cancer-related death in the United States, the overall incidence and mortality from the disease have declined in recent decades. In contrast, there has been a steady increase in the incidence of CRC in individuals under 50 years of age. Hereditary syndromes contribute disproportionately to early onset CRC (EOCRC). These include microsatellite instability high (MSI+) tumors arising in patients with Lynch Syndrome. However, most EOCRCs are not associated with familial syndromes or MSI+ genotypes. Comprehensive genomic profiling has provided the basis of improved more personalized treatments for older CRC patients. However, less is known about the basis of sporadic EOCRC. To define the genomic landscape of EOCRC we used DNA content flow sorting to isolate diploid and aneuploid tumor fractions from 21 non-hereditary cases. We then generated whole exome mutational profiles for each case and whole genome copy number, telomere length, and EGFR immunohistochemistry (IHC) analyses on subsets of samples. These results discriminate the molecular features of diploid and aneuploid EOCRC and provide a basis for larger population-based studies and the development of effective strategies to monitor and treat this emerging disease.

The incidence of young-onset colorectal cancer (yCRC) has been increasing in recent decades, but little is known about the gut microbiome of these patients. Most studies have focused on old-onset CRC (oCRC), and it remains unclear whether CRC signatures derived from old patients are valid in young patients. To address this, we assembled the largest yCRC gut metagenomes to date from two independent cohorts and found that the CRC microbiome had limited association with age across adulthood. Differential analysis revealed that well-known CRC-associated taxa, such as Clostridium symbiosum, Peptostreptococcus stomatis, Parvimonas micra and Hungatella hathewayi were significantly enriched (false discovery rate <0.05) in both old- and young-onset patients. Similar strain-level patterns of Fusobacterium nucleatum, Bacteroides fragilis and Escherichia coli were observed for oCRC and yCRC. Almost all oCRC-associated metagenomic pathways had directionally concordant changes in young patients. Importantly, CRC-associated virulence factors (fadA, bft) were enriched in both oCRC and yCRC compared to their respective controls. Moreover, the microbiome-based classification model had similar predication accuracy for CRC status in old- and young-onset patients, underscoring the consistency of microbial signatures across different age groups.

The incidence of early-onset colorectal cancer (EOCRC, diagnosed in patients under the age of 50 years) has been increasing around the world. Here, we aimed to systematically identify distinctive features of EOCRC.

From 2020 to 2021, we conducted a nationwide survey in 19 hospitals, collecting data on advanced CRC patients' demographics, clinical features, disease knowledge, medical experiences, expenditures, and health-related quality of life (HRQOL). We compared these features between EOCRC and late-onset colorectal cancer (LOCRC, ≥ 50 years old) groups and analyzed the association between EOCRC and HRQOL using multivariate linear regression.

In total, 991 patients with EOCRC and 3581 patients with LOCRC were included. Compared to the LOCRC group, the EOCRC group had higher levels of education, were more informed about the risk factors for CRC, were more likely to have widespread metastases throughout the body, were more inclined to undergo gene testing, and were more likely to opt for targeted therapy, radiotherapy, and chemotherapy. However, HRQOL in the EOCRC group was similar to that of the LOCRC group, and no significant association was observed between EOCRC and HRQOL (beta: -0.753, P value: 0.307).

In Chinese patients, EOCRC patients had more aggressive features. Despite undergoing more intensified treatments and gene testing, they had similar HRQOL compared with LOCRC. These findings advocate for a more tailored approach to treatment, especially for young CRC patients with advanced TNM stages and metastasis.

Colorectal liver metastasis (CRLM) exhibits highly heterogeneity, with clinically and molecularly defined subgroups that differ in their prognosis. The aim of this study is to explore whether left-sided tumors is clinically and gnomically distinct from right-sided tumors in CRLM.

This retrospective study included 1,307 patients who underwent primary tumor and metastases resection at three academic centers in China from January 1, 2012, to December 31, 2020. Propensity score matching with 1:1 ratio matching was performed. The prognostic impact of tumor sidedness was determined after stratifying by the KRAS mutational status. Moreover, whole-exome sequencing (WES) of 200 liver tumor tissues were performed to describe the heterogeneity across the analysis of somatic and germline profiles.

The median follow-up was 68 months. Matching yielded 481 pairs of patients. Compared to right-sided CRLM, left-sided patients experienced with better 5-year overall survival (OS) in surgery responsiveness, with a 14.6 lower risk of death [hazard ratio (HR), 1.36, 95% confidence interval (CI), 1.10-1.69, P=0.004]. Interaction between tumor sidedness and KRAS status was statistically significant: left-sidedness was associated with better prognosis among KRAS wild-type patients (HR 1.71; 95% CI: 1.20-2.45; P=0.003), but not among KRAS mutated-type patients. Integrated molecular analyses showed that right-sided tumors more frequently harbored TP53, APC, KRAS, and BRAF alterations, and identified a critical role of KRAS mutation in correlation with their survival differences. Higher pathogenic germline variants were identified in the right-sided tumors compared with left-sided tumors (29.3% vs. 15.5%, P=0.03).

We demonstrated that the prognostic impacts of tumor sidedness in CRLM is restricted patients with KRAS wild-type tumors. Tumor sidedness displays considerable clinical and molecular heterogeneity that may associate with their therapy benefits and prognosis.

Metabolic dysfunction associated with obesity leads to a chronic pro-inflammatory state with systemic effects, including the alteration of macrophage metabolism. Tumor-associated macrophages have been linked to the formation of cancer through the production of metabolites such as itaconate. Itaconate downregulates peroxisome proliferator-activated receptor gamma as a tumor-suppressing factor and upregulates anti-inflammatory cytokines in M2-like macrophages. Similarly, leptin and adiponectin also influence macrophage cytokine expression and contribute to the progression of colorectal cancer via changes in gene expression within the PI3K/AKT pathway. This pathway influences cell proliferation, differentiation, and tumorigenesis. This work provides a review of obesity-related hormones and inflammatory mechanisms leading to the development and progression of early-onset colorectal cancer (EOCRC). A literature search was performed using the PubMed and Cochrane databases to identify studies related to obesity and EOCRC, with keywords including 'EOCRC', 'obesity', 'obesity-related hormones', 'itaconate', 'adiponectin', 'leptin', 'M2a macrophage', and 'microbiome'. With this concept of pro-inflammatory markers contributing to EOCRC, increased use of chemo-preventative agents such as aspirin may have a protective effect. Elucidating this association between obesity-related, hormone/cytokine-driven inflammatory effects with EOCRC may help lead to new therapeutic targets in preventing and treating EOCRC.

Immunotherapy has transformed treatment for various types of malignancy. However, the benefit of immunotherapy is limited to a minority of patients with mismatch-repair-deficient (dMMR) and microsatellite instability-high (MSI-H) (dMMR-MSI-H) colorectal cancer (CRC). Understanding the complexity and heterogeneity of the tumor immune microenvironment (TIME) and identifying immune-related CRC subtypes will improve antitumor immunotherapy. Here, we review the current status of immunotherapy and typing schemes for CRC. Immune subtypes have been identified based on TIME and prognostic gene signatures that can both partially explain clinical responses to immune checkpoint inhibitors and the prognosis of patients with CRC. Identifying immune subtypes will improve understanding of complex CRC tumor heterogeneity and refine current immunotherapeutic strategies.

Early-onset colorectal cancer (age under 50 years) (EOCRC) is an entity of undeniable importance, both because of its growing incidence, and the population it affects. Other current reviews emphasize the essential points regarding the clinical management and knowledge of its molecular bases. However, we intend to go one step further. With the increased significance of patient participation and disease experience in mind, we have integrated the voice of the patient to show the weaknesses and the needs, and next steps in the advancement of knowledge and management of EOCRC. This integrative review of the different perspectives, clinical, research and the patients themselves, can therefore be defined as an integrative needs assessment. Hence, this may be a first step in working towards an essential homogeneity of definitions and action.

There is an urgent need for markers to predict the efficacy of different chemotherapy drugs. Herein, we examined whether microsatellite instability (MSI) status can predict tumor multidrug sensitivity and explored the underlying mechanisms. We downloaded data from several public databases. Drug sensitivity was compared between the high microsatellite instability (MSI-H) and microsatellite-stable/low microsatellite instability (MSS/MSI-L) groups. In addition, we performed pathway enrichment analysis and cellular chemosensitivity assays to explore the mechanisms by which MSI status may affect drug sensitivity and assessed the differences between drug-treated and control cell lines. We found that multiple MSI-H tumors were more sensitive to a variety of chemotherapy drugs than MSS/MSI-L tumors, and especially for CRC, chemosensitivity is enhanced through the downregulation of DDR pathways such as NHEJ. Additional DNA damage caused by chemotherapeutic drugs results in further downregulation of DDR pathways and enhances drug sensitivity, forming a cycle of increasing drug sensitivity.

Despite a recent overall decrease in colorectal cancer (CRC) incidence and mortality, there has been a significant rise in CRC diagnoses in young adults. Early onset colorectal cancer (EOCRC) is defined as CRC diagnosed before the age of 50. Possible predisposing conditions include not only genetic syndromes but also other risk factors, such as microbiome alteration, antibiotic exposure, obesity, diabetes mellitus, and inflammatory bowel disease. EOCRC tends to be diagnosed later than in the older counterpart because of a lack of awareness and the fact that screening for CRC usually starts at the age of 50. Furthermore, CRC in young adults seems to be related to unique molecular features and more aggressive clinical behavior. This paper aims to provide an in-depth review of this poorly understood subject, with a comprehensive review of the state of the art and considerations for future perspectives.

The incidence of early-onset colorectal cancer (EO-CRC, in patients younger than 50) is increasing worldwide. The specific gene signatures in EO-CRC patients are largely unknown. Since EO-CRC with microsatellite instability is frequently associated with Lynch syndrome, we aimed to comprehensively characterize the tumor microenvironment (TME) and gene expression profiles of EO-CRC with microsatellite stable (MSS-EO-CRC). Here, we demonstrated that MSS-EO-CRC has a similar pattern of tumor-infiltrating immune cells, immunotherapeutic responses, consensus molecular subtypes, and prognosis as late-onset CRC with MSS (MSS-LO-CRC). 133 differential expressed genes were identified as unique gene signatures of MSS-EO-CRC. Moreover, we established a risk score, which was positively associated with PD-L1 expression and could reflect both the level of tumor-infiltrating immune cells and the prognosis of MSS-EO-CRC patients. Application of this score on the anti-PD-L1 treatment cohort demonstrated that the low-risk score group has significant therapeutic advantages and clinical benefits. In addition, candidate driver genes were identified in the different-sidedness of MSS-EO-CRC patients. Altogether, MSS-EO-CRC exhibits distinct molecular profiles that differ from MSS-LO-CRC even though they have a similar TME characterization and survival pattern. Our risk score appears to be robust enough to predict prognosis and immunotherapeutic response and therefore could help to optimize the treatment of MSS-EO-CRC.

Although the incidence of late-onset colorectal cancer (LOCRC) has decreased, the incidence of early-onset colorectal cancer (EOCRC) is still rising dramatically. Heterogeneity in the genomic, biological, and clinicopathological characteristics between EOCRC and LOCRC has been revealed. Therefore, the previous prognostic models based on the total CRC patient population might not be suitable for EOCRC patients. Here, we constructed a prognostic classifier to enhance the precision of individualized treatment and management of EOCRC patients.

EOCRC expression data were downloaded from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. The regulatory pathways were explored by gene set enrichment analysis (GSEA). The prognostic model was developed by univariate Cox-LASSO-multivariate Cox regression analyses of GEO samples. TCGA samples were used to verify the model. The expression and mutation profiles and immune landscape of the high-risk and low-risk cohorts were analyzed and compared. Finally, the expression and prognostic value of the model genes were verified by immunohistochemistry and qRT‒PCR analysis.

The cell cycle was identified as the most significantly enriched oncological signature of EOCRC. Then, a 4-gene prognostic signature comprising MCM2, INHBA, CGREF1, and KLF9 was constructed. The risk score was an independent predictor of overall survival. The area under the curve values of the classifier for 1-, 3-, and 5-year survival were 0.856, 0.893, and 0.826, respectively, in the training set and 0.749, 0.858, and 0.865, respectively, in the validation set. Impaired DNA damage repair capability (p < 0.05) and frequent PIK3CA mutations (p < 0.05) were found in the high-risk cohort. CD8 T cells (p < 0.05), activated memory CD4 T cells (p < 0.01), and activated dendritic cells (p < 0.05) were clustered in the low-risk group. Finally, we verified the expression of MCM2, INHBA, CGREF1, and KLF9. Their prognostic value was closely related to age.

In this study, a robust prognostic classifier for EOCRC was established and validated. The findings may provide a reference for individualized treatment and medical decision-making for patients with EOCRC.

The purpose of this study is to construct a novel and practical nomogram and risk stratification system to accurately predict cancer-specific survival (CSS) of early-onset locally advanced rectal cancer (EO-LARC) patients.

A total of 2440 patients diagnosed with EO-LARC between 2010 and 2019 were screened from the Surveillance, Epidemiology, and End Results (SEER) database. The pool of potentially eligible patients was randomly divided into two groups: a training cohort (N=1708) and a validation cohort (N=732). The nomogram was developed and calibrated using various methods, including the coherence index (C-index), receiver operating characteristic curve (ROC), calibration curves, and decision curves (DCA). A new risk classification system was established based on the nomogram. To compare the performance of this nomogram to that of the American Joint Committee on Cancer (AJCC) staging system, DCA, net reclassification index (NRI), and integrated discrimination improvement (IDI) were employed.

Seven variables were included in the model. The area under the ROC curve (AUC) for the training cohort was 0.766, 0.736, and 0.731 at 3, 6, and 9 years, respectively. Calibration plots displayed good consistency between actual observations and the nomogram's predictions. The DCA curve further demonstrated the validity of the nomination form in clinical practice. Based on the scores of the nomogram, all patients were divided into a low-risk group, a middle-risk group, and a high-risk group. NRI for the 3-, 6-, and 9-year CSS(training cohort: 0.48, 0.45, 0.52; validation cohort: 0.42, 0.37, 0.37), IDI for the 3-, 6-, and 9-year CSS (training cohort: 0.09, 0.10, 0.11; validation cohort: 0.07, 0.08, 0.08). The Kaplan-Meier curve revealed that the new risk classification system possesses a more extraordinary ability to identify patients in different risk groups than the AJCC staging.

A practical prognostic nomogram and novel risk classification system have been developed to efficiently predict the prognosis of EO-LARC. These tools can serve as a guide to individualize patient treatment and improve clinical decision-making.

Cancers in young adults (commonly described as early-onset [EO] cancer) represent a group of malignancies that have unique and challenging biology and genetic, treatment, social, and psychological implications. Even more concerning is a rising trend of EO cancers in multiple tumor types. Research and investigation in EO cancers will help elucidate mechanisms of carcinogenesis, differences in biology and response to treatment, and the need for multidisciplinary care to ensure comprehensive treatment and support for young patients.

Colorectal cancer diagnosed in individuals under 50 years old is called early-onset colorectal cancer (EOCRC), and its incidence has been rising worldwide. Simultaneously occurring with increasing obesity, this worrisome trend is partly explained by the strong influence of dietary elements, particularly fatty, meaty, and sugary food. An animal-based diet, the so-called Western diet, causes a shift in dominant microbiota and their metabolic activity, which may disrupt the homeostasis of hydrogen sulfide concentration. Bacterial sulfur metabolism is recognized as a critical mechanism of EOCRC pathogenesis. This review evaluates the pathophysiology of how a diet-associated shift in gut microbiota, so-called the microbial sulfur diet, provokes injuries and inflammation to the colonic mucosa and contributes to the development of CRC.

Early-onset colorectal cancer (EOCRC) has been rising in global prevalence and incidence over the past several decades. Environmental influences, including generational lifestyle changes and rising obesity, contribute to these increased rates. While the rise in EOCRC is best documented in western countries, it is seen throughout the world, although EOCRC may have distinct genetic mutations in patients of different ethnic backgrounds. Pathological and molecular characterizations show that EOCRC has a distinct presentation compared with later-onset colorectal cancer (LOCRC). Recent studies have identified DNA, RNA, and protein-level alterations unique to EOCRC, revealing much-needed biomarkers and potential novel therapeutic targets. Many molecular EOCRC studies have been performed with Caucasian and Asian EOCRC cohorts, however, studies of other ethnic backgrounds are limited. In addition, certain molecular characterizations that have been conducted for LOCRC have not yet been repeated in EOCRC, including high-throughput analyses of histone modifications, mRNA splicing, and proteomics on large cohorts. We propose that the complex relationship between cancer and aging should be considered when studying the molecular underpinnings of EOCRC. In this review, we summarize current EOCRC literature, focusing on sporadic molecular alterations in tumors, and their clinical implications. We conclude by discussing current challenges and future directions of EOCRC research efforts.

Molecular features underlying colorectal cancer disparities remain uncharacterized. Here, we investigated somatic mutation patterns by race/ethnicity and sex among 5,856 non-Hispanic white (NHW), 535 non-Hispanic Black (NHB), and 512 Asian/Pacific Islander (API) patients with colorectal cancer (2,016 early-onset colorectal cancer patients: sequencing age <50 years). NHB patients with early-onset nonhypermutated colorectal cancer, but not API patients, had higher adjusted tumor mutation rates than NHW patients. There were significant differences for LRP1B, FLT4, FBXW7, RNF43, ATRX, APC, and PIK3CA mutation frequencies in early-onset nonhypermutated colorectal cancers between racial/ethnic groups. Heterogeneities by race/ethnicity were observed for the effect of APC, FLT4, and FAT1 between early-onset and late-onset nonhypermutated colorectal cancer. By sex, heterogeneity was observed for the effect of EP300, BRAF, WRN, KRAS, AXIN2, and SMAD2. Males and females with nonhypermutated colorectal cancer had different trends in EP300 mutations by age group. These findings define genomic patterns of early-onset nonhypermutated colorectal cancer by race/ethnicity and sex, which yields novel biological clues into early-onset colorectal cancer disparities.

NHBs, but not APIs, with early-onset nonhypermutated colorectal cancer had higher adjusted tumor mutation rates versus NHWs. Differences for FLT4, FBXW7, RNF43, LRP1B, APC, PIK3CA, and ATRX mutation rates between racial/ethnic groups and EP300, KRAS, AXIN2, WRN, BRAF, and LRP1B mutation rates by sex were observed in tumors of young patients. See related commentary by Shen et al., p. 530 . This article is highlighted in the In This Issue feature, p. 517.

Early-onset colorectal cancer (EOCRC) has been increasing in incidence worldwide but its genomic pathogenesis is mostly undetermined. This study aimed to identify robust EOCRC-specific gene expression patterns in non-familial adenomatous polyposis (FAP) and non-hereditary nonpolyposis colorectal cancer syndrome (HNPCC) EOCRC.

We first performed gene expression profiling analysis using RNA sequencing of discovery cohort comprised of 49 EOCRC (age <50) and 50 late-onset colorectal cancer (LOCRC) (age >70) specimens. To obtain robust gene expression data from this analysis, we validated differentially expressed genes (DEGs) through TCGA cohort (EOCRC:59 samples, LOCRC:229 samples) and our validation cohort (EOCRC:72 samples, LOCRC:43 samples) using real-time RT-PCR. After the validation of DEGs, we validated the selected gene at protein levels using Western blotting. To identify whether genomic methylation regulates the expression of a particular gene, we selected methylation sites using The Cancer Genome Atlas (TCGA) datasets and validated them by pyrosequencing in our validation cohort.

The EOCRC patients included in this study had significantly more prominent family history of cancer than the LOCRC patients (23 [46.9%] vs. 13 [26%], p = 0.050). Alanyl aminopeptidase (ANPEP) was significantly downregulated in the EOCRC tissues (FC = 1.78, p = 0.0007) and was also commonly downregulated in the TCGA cohort (FC = -1.08, p = 0.0021). Moreover, the ANPEP mRNA and protein expression levels were significantly downregulated in the EOCRC tissues of our validation cohort (p = 0.037 and 0.027). In comparisons of the normal and tumor tissues in public datasets, the ANPEP level was significantly lower in the tumor tissue in the TCGA dataset (p < 2.2 × 10^-16 ) and GSE196006 dataset (p = 0.0005). Furthermore, the ANPEP expression level did not show a decreasing tendency at a young age in the normal colon tissue of the GTEx dataset. Lastly, the hypermethylation of cg26222247 in ANPEP was identified to be weakly associated with reduced ANPEP expression in our EOCRC cohort.

The reduced expression of ANPEP was identified as a novel biomarker of non-FAP and non-HNPCC EOCRC.

Early-onset colorectal cancer (EOCRC) incidence is increasing worldwide. Efforts are directed to understand the biological and clinical signatures of EOCRC compared to late-onset colorectal cancer (LOCRC). EOCRC is thought to present differently across different ethnic groups and geographical regions. This study was an attempt to contribute with data from the Arab world toward the understanding of the clinicopathological parameters of EOCRC compared to LOCRC. Data from 254 CRC patients diagnosed at Sultan Qaboos University Hospital from the period 2015-2020 were studied. About 32.6% of all diagnosed CRC patients are below 50 years old, with no differences in gender distribution between EOCRC and LOCRC (p-value 0.417). Rectal involvement and tumor laterality were comparable among the two groups. Adenocarcinoma accounts for 83.3% and 94.2% of EOCRC and LOCRC, respectively. More mucinous and signet ring adenocarcinoma (8.3% each) were reported in EOCRC than LOCRC (2.9% and 2.2%, respectively). MLH1 and PMS2 loss are more common among LOCRC, but MSH6 loss is more frequent in EOCRC. The overall survival of EOCRC and LOCRC was comparable (median survival 64.88 and 67.24 months, respectively). This study showed comparable clinicopathological parameters between EOCRC and LOCRC from Arabs, which adds to the bigger picture of understand the disease.

Metastases at regional lymph nodes could easily occur in patients with high-histological-grade colorectal cancer (CRC). However, few models were built on the basis of lymph nodes to predict the outcome of patients with histological grades III-IV CRC.

Data in the Surveillance, Epidemiology, and End Results databases were used. Univariate and multivariate analyses were performed. A personalized prediction model was built in accordance with the results of the analyses. A nomogram was tested in two datasets and assessed using a calibration curve, a consistency index (C-index), and an area under the curve (AUC).

A total of 14,039 cases were obtained from the database. They were separated into two groups (9828 cases for constructing the model and 4211 cases for validation). Logistic and Cox regression analyses were then conducted. Factors such as log odds of positive lymph nodes (LODDS) were utilized. Then, a personalized prediction model was established. The C-index in the construction and validation groups was 0.770. The 1-, 3-, and 5-year AUCs were 0793, 0.828, and 0.830 in the construction group, respectively, and 0.796, 0.833, and 0.832 in the validation group, respectively. The calibration curves showed well consistency in the 1-, 3- and 5-year OS between prediction and reality in both groups.

The nomogram built based on LODDS exhibited considerable reliability and accuracy.

Cancer tissue samples contain cancer cells and non-cancer cells with each biopsied site containing distinct proportions of these populations. Consequently, assigning useful tumor subtypes based on gene expression measurements from clinical samples is challenging. We applied a blind source separation approach to extract cancer cell-intrinsic gene expression patterns within clinical tumor samples of colorectal cancer. After a blind source separation, we found that a cancer cell-intrinsic gene expression program unique to each patient exists in the "residual" expression profile remaining after separation of the gene expression data. We performed a consensus clustering analysis of the extracted gene expression profiles to identify novel and robust cancer cell-intrinsic subtypes. We validated the identified subtypes using an independent clinical gene expression dataset. The cancer cell-intrinsic subtypes are independent of biopsy site and provided prognostic information in addition to currently available clinical and molecular variables. After validating this approach in colorectal cancer, we further identified novel tumor subtypes with unique clinical information across multiple types of cancer. These cancer cell-intrinsic molecular subtypes provide novel prognostic value for clinical assessment of cancer.

The incidence of sporadic young-onset colorectal cancer (yCRC) is increasing. Compared with old-onset colorectal cancer (oCRC), yCRC has different clinical and molecular characteristics. However, the difference in the tumor microenvironment (TME) between yCRC and oCRC remains unclear.

Fourteen untreated CRC tumor samples were subjected to single-cell RNA sequencing analysis.

B cells and naïve T cells are enriched in yCRC, while effector T cells and plasma cells are enriched in oCRC. Effector T cells of yCRC show decreased interferon-gamma response and proliferative activity; meanwhile, Treg cells in yCRC show stronger oxidative phosphorylation and TGF-β signaling than that in oCRC. The down-regulated immune response of T cells in yCRC may be regulated by immune and malignant cells, as we observed a downregulation of antigen presentation and immune activations in B cells, dendritic cells, and macrophages. Finally, we identified malignant cells in yCRC and oCRC with high heterogeneity and revealed their interactions with immune cells in the TME.

Our data reveal significant differences of TME between yCRC and oCRC, of which the TME of yCRC is more immunosuppressive than oCRC. Malignant cells play an essential role in the formation of the suppressive tumor immune microenvironment.

The observed increase in the incidence of early-onset colorectal cancer (EOCRC) is being driven by sporadic cases, but the molecular characteristics of these tumors are not fully understood. Our objective was to investigate the prevalence of microsatellite instability (MSI) and selected mutations in sporadic EOCRC, and their association with survival.

Firstly, we compared the prevalence of molecular characteristics and survival within a population-based cohort study of 652 stage II and III colon cancer patients in Northern Ireland, comparing sporadic early-onset (<50 years, n = 35) with older (60-69 years, n = 179) patients. Secondly, a systematic review for studies reporting the prevalence of MSI, mismatch repair deficiency (dMMR), or BRAF, KRAS, NRAS, PIK3CA, and TP53 mutations in sporadic EOCRC was conducted. A meta-analysis was performed to calculate pooled estimates of the prevalence of molecular features in sporadic EOCRC.

Firstly, within the cohort study, EOCRC patients did not have a significantly increased risk of colorectal cancer-specific death (adjusted hazard ratio 1.20; 95% confidence interval [CI] 0.61-2.39) compared with 60- to 69-year-olds. Second, 32 studies were included in the systematic review. The pooled analysis estimated a prevalence of 10% (95% CI 7%-14%) for MSI high/dMMR in sporadic EOCRC. BRAF and KRAS mutations had a prevalence of 1% (95% CI 0%-3%) and 32% (95% CI 23%-40%), respectively.

The molecular characteristics of sporadic EOCRC differ from those of cancers in older adults, particularly regarding reduced prevalence of BRAF mutations. Ten percent of sporadic EOCRC display MSI high/dMMR. Further studies are needed to address survival in sporadic EOCRC cases and whether molecular profiles influence EOCRC outcomes in this patient group.