Hereditary colorectal cancer (CRC) syndromes account for up to 5% of CRC. Patients have an increased risk of CRC and extracolonic cancers, both of which develop at an early age. The main polyposis syndromes include familial adenomatous polyposis, MYH-associated polyposis, Peutz-Jeghers syndrome, juvenile polyposis syndrome, and PTEN hamartoma syndrome. The non-polyposis syndromes include Lynch syndrome and familial colorectal cancer type X. Each of the syndromes have distinct but sometimes overlapping phenotypes. Clinical evaluation and ultimately the underlying germline genetic pathogenic variants define the syndromes. Each syndrome has polyp, CRC, and extracolonic risks and management is based on early and timely surveillance with therapeutic and often extended prophylactic surgery. Surgical intervention strategies are individualized, considering not only the earlier onset of malignancies and heightened risks for metachronous cancers but also the patient's needs and quality of life. This article reviews the different diagnostic approaches to hereditary CRC and highlights subsequent disease-specific management and surgical decision-making strategies.

Patients with familial adenomatous polyposis (FAP) develop early colorectal adenomas and if left untreated, progression to cancer is an inevitable event. Prophylactic surgery does not prevent further development of cancer in the rectal remnant, rectal cuff in patients with ileal pouch anal anastomosis (IPAA) and even on the ileal mucosa of the pouch body. The aim of this review is to assess long-term rates of cancer and adenoma development in patients with FAP after prophylactic surgery and to summarise current recommendations for endoscopic management and surveillance of these patients.

A systematic literature search of studies from January 1946 through to June 2023 was conducted using the PRISMA checklist. The electronic database PubMed was searched.

Fifty-four papers involving 5010 patients were reviewed. Cancer rate in the rectal remnant was 8.8-16.7% in the western population and 37% in the eastern population. The cumulative risk of cancer 30 years after surgery was 24%. Mortality due to cancer in the rectal remnant is 1.1-11.1% with a 5-year survival rate of 55%. The adenoma rate after primary IPAA was 9.4-85% with a cumulative risk of 85% 20 years after surgery and a cumulative risk of 12% for advanced adenomas 10 years after surgery. Cumulative risk for adenomas after ileorectal anastomosis (IRA) was 85% after 5 and 100% after 10 years. Adenomas developed more frequently after stapled (33.9-57%) compared to hand-sewn (0-33%) anastomosis. We identified reports of 45 cancers in patients after IPAA of which 30 were in the pouch body and 15 in the rectal cuff or at the anastomosis.

There was a significant incidence of cancer and adenomas in the rectal remnant and ileal pouch of FAP patients during the long-term follow-up. Regular endoscopic surveillance is recommended, not only in IRA patients, but also in pouch patients after proctocolectomy.

Advances in molecular genetics have revolutionized our understanding of the pathogenesis, progression, and therapeutic options for treating gastrointestinal (GI) cancers. This chapter provides a comprehensive overview of the molecular landscape of GI cancers, focusing on key genetic alterations implicated in tumorigenesis across various anatomical sites including GIST, colon and rectum, and pancreas. Emphasis is placed on critical oncogenic pathways, such as mutations in tumor suppressor genes, oncogenes, chromosomal instability, microsatellite instability, and epigenetic modifications. The role of molecular biomarkers in predicting prognosis, guiding treatment decisions, and monitoring therapeutic response is discussed, highlighting the integration of genomic profiling into clinical practice. Finally, we address the evolving landscape of precision oncology in GI cancers, considering targeted therapies and immunotherapies.

Ampullary adenomas (AAs), common in familial adenomatous polyposis (FAP), are precursors to ampullary carcinoma. We assessed the natural history of AAs and factors associated with clinically significant progression (CSP).

Consecutive FAP patients with AAs and at least 2 EGDs were identified from a hereditary GI cancer registry. We assessed the incidence of CSP (increase in size to ≥10 mm and/or development of advanced histology) of AAs. Clinical, endoscopic, and pathologic features between patients with CSP and nonprogressors were compared.

One hundred forty-three patients with AAs were included. Over a median follow-up of 7.8 years (interquartile range, 4.3-11.1), 41 patients (28.6%) developed CSP for an incidence of 35 per 1000 patient-years. Of 143 patients, 22 (15.6%) progressed to AAs ≥10 mm, 12 (8.5%) progressed to advanced histology, and 7 (4.9%) progressed both in size and histology. Two patients (1.4%) developed ampullary cancer. Male gender, abnormal appearance of the papilla at initial AA detection, prior cholecystectomy, and personal history of extracolonic malignancy were associated with CSP. Neither Spigelman stage nor the adenomatous polyposis coli gene pathogenic variants were associated with CSP. An intervention specifically for AA and not duodenal polyposis was performed in 24% of patients with AAs, including endoscopic papillectomy in 23 patients and duodenectomy in 3 patients at a median observation of 8.2 years.

Most FAP patients with AAs did not experience CSP or require resection over 8 years of surveillance. Ampullary cancer was rare. Male gender, abnormal appearance of the papilla at AA detection, cholecystectomy, and history of extracolonic malignancy were associated with CSP. Our findings favor endoscopic surveillance of AAs over expedited resection for most patients with FAP.

To achieve excellent postoperative bowel function in familial adenomatous polyposis (FAP) patients, it is important to reconstruct the digestive tract. The aim of this study is to preliminarily discuss the advantages of total proctocolectomy with straight ileoanal anastomosis (TPC-SIAA) plus pedicled omental transposition for FAP.

A retrospective study was carried out in two hospitals analysing data for FAP patients who underwent surgical treatments between 2015 and 2021. Perioperative outcomes and early and mid-term anal functions were analysed.

After excluding 4 patients who underwent total proctocolectomy with permanent ileostomy, 10 patients were enrolled in the study. Among the 10 patients, 3 received TPC-SIAA plus pedicled omental transposition, 3 received total proctocolectomy with ileal pouch-anal anastomosis (TPC-IPAA), and 4 received total colectomy with ileal pouch-rectal anastomosis (TC-IPRA). Except for one case conversion to laparotomy, laparoscopic surgery was performed for the other cases. The incidence of early postoperative complications was apparently higher with pouch anastomosis (57.1%) than straight anastomosis (0%). Frequencies of bowel movement and low anterior resection syndrome (LARS) score were higher for TPC-SIAA than the other two surgical procedures in the early term; over time, however, the frequencies of bowel movement and LARS score both showed a decreasing trend. In addition, combined with anorectal pressure detection and magnetic resonance imaging defecography at the 3rd month after TPC-SIAA plus pedicled omental transposition, defecation coordination was good. The dynamics and receptivity of the new rectum tended to be as expected.

Although the three surgical procedures are safe and feasible surgical options for FAP, TPC-SIAA plus pedicled omental transposition is more consistent with intestinal physiology, with good intestinal compliance, and anal function tended to be as expected over time. Nevertheless, more extensive studies are needed to confirm these benefits.

Colectomy in patients with adenomatous polyposis (AP) syndromes demands good oncological and surgical outcome. Total colectomy with ileorectal anastomosis (TC-IRA) is one surgical option for these patients. Anastomotic leakage rates of 11% have been reported following TC-IRA. Ileo-distal sigmoid anastomosis (IDSA) is a recent modification of our practice. Our aim was to compare postoperative outcome in patients with AP following near-total colectomy with IDSA (NT-IDSA) and TC-IRA at a single institution.

A prospectively maintained database was reviewed to identify patients with AP who underwent laparoscopic NT-IDSA and TC-IRA. Patient demographics, early morbidity and mortality and outcome of endoscopic surveillance were evaluated.

A total of 191 patients with AP underwent laparoscopic colectomy between 2006 and 2017, of whom 139 (72.8%) underwent TC-IRA and 52 (27.2%) NT-IDSA. The median age at surgery in the TC-IRA and NT-IDSA groups was 20 years (IQR 17-45) and 27 years (IQR 19-50), respectively. Grade II complications were comparable between the two groups. There were no anastomotic leakages in the NT-IDSA group compared with 15 (10.8%) in the TC-IRA group (P = 0.0125) and no reoperation in the NT-IDSA group compared with 17 (12.2%) in the TC-IRA group (P = 0.008). The frequency of polypectomies per flexible sigmoidoscopy was comparable between the two groups.

This study demonstrates that laparoscopic NT-IDSA for polyposis is associated with a significant improvement in anastomotic leakage rates and surgical outcome. It is too soon to tell whether NT-IDSA alters the need for further intervention, either endoscopic polypectomy or further surgery.

Heritable factors account for approximately 35% of colorectal cancer (CRC) risk, and almost 30% of the population in the UK have a family history of CRC. The quantification of an individual's lifetime risk of gastrointestinal cancer may incorporate clinical and molecular data, and depends on accurate phenotypic assessment and genetic diagnosis. In turn this may facilitate targeted risk-reducing interventions, including endoscopic surveillance, preventative surgery and chemoprophylaxis, which provide opportunities for cancer prevention. This guideline is an update from the 2010 British Society of Gastroenterology/Association of Coloproctology of Great Britain and Ireland (BSG/ACPGBI) guidelines for colorectal screening and surveillance in moderate and high-risk groups; however, this guideline is concerned specifically with people who have increased lifetime risk of CRC due to hereditary factors, including those with Lynch syndrome, polyposis or a family history of CRC. On this occasion we invited the UK Cancer Genetics Group (UKCGG), a subgroup within the British Society of Genetic Medicine (BSGM), as a partner to BSG and ACPGBI in the multidisciplinary guideline development process. We also invited external review through the Delphi process by members of the public as well as the steering committees of the European Hereditary Tumour Group (EHTG) and the European Society of Gastrointestinal Endoscopy (ESGE). A systematic review of 10 189 publications was undertaken to develop 67 evidence and expert opinion-based recommendations for the management of hereditary CRC risk. Ten research recommendations are also prioritised to inform clinical management of people at hereditary CRC risk.

To investigate the recent Japanese prevalence of thyroid cancer and its characteristics in familial adenomatous polyposis (FAP) patients, through the development of surveillance programs.

The subjects of this study were 282 (93.1%) FAP patients for whom information on thyroid cancer was available, from among 303 patients registered in "the Retrospective Cohort Study of Familial Adenomatous Polyposis in Japan" database. We evaluated the prevalence and risk factors for thyroid cancer and integrated and/or compared our findings with those of previous reports, using a systematic review, including a meta-analysis.

Thyroid cancer was diagnosed in 16 women (11.4%) and 2 men (1.4%), at 17-41 years and 39-57 years of age, respectively. The prevalence of thyroid cancer was 6.4%, with a female-to-male ratio of 8:1, which is comparable to reports from other countries. A young age of < 33 years at the FAP diagnosis and female gender were identified as independent risk factors for thyroid cancer.

FAP-associated thyroid cancer predominantly affects young women, both in Japan and other countries. Since FAP is generally diagnosed when patients are in their 20 s or older, regular screening for thyroid cancer is recommended for all FAP patients, but especially women, from their early 20 s.

Hereditary colorectal cancer accounts for less than 5% of all colorectal cancer cases. Some of the unique characteristics that are commonly encountered in cases of hereditary colorectal cancer include early age at onset, synchronous/metachronous occurrence of the cancer, and association with multiple cancers in other organs, necessitating different management from sporadic colorectal cancer. While the diagnosis of familial adenomatous polyposis might be easy because usually 100 or more adenomas that develop in the colonic mucosa are in this condition, Lynch syndrome, which is the most commonly associated disease with hereditary colorectal cancer, is often missed in daily medical practice because of its relatively poorly defined clinical characteristics. In addition, the disease concept and diagnostic criteria for Lynch syndrome, which was once called hereditary non-polyposis colorectal cancer, have changed over time with continual research, thereby possibly creating confusion in clinical practice. Under these circumstances, the JSCCR Guideline Committee has developed the "JSCCR Guidelines 2016 for the Clinical Practice of Hereditary Colorectal Cancer (HCRC)," to allow delivery of appropriate medical care in daily practice to patients with familial adenomatous polyposis, Lynch syndrome, or other related diseases. The JSCCR Guidelines 2016 for HCRC were prepared by consensus reached among members of the JSCCR Guideline Committee, based on a careful review of the evidence retrieved from literature searches, and considering the medical health insurance system and actual clinical practice settings in Japan. Herein, we present the English version of the JSCCR Guidelines 2016 for HCRC.

To identify prognostic factors and to correlate APC mutations with clinical features, including extracolic manifestations.

One hundred thirty-five patients who underwent surgical procedures for familial adenomatous polyposis (FAP) were included. FAP was diagnosed when the number of adenomatous polyps was > 100. Data related to patient, extracoloic manifestations, cancer characteristics, operative procedure, follow up and surveillance were collected. APC mutation testing was performed in the 30 most recent patients. DNA was extracted from peripheral blood and polymerase chain reaction products using 31 primer pairs on APC gene were sequenced. A retrospective study was performed to investigate a causal relationship between prognosis and feature of patient.

The mean age of the 51 patients with colorectal cancer (CRC) was older than that of those without CRC (30.5 vs 36.9, P = 0.002). Older individuals were more likely to have colon cancer at the time of FAP diagnosis [odds ratio, 4.75 (95%CI: 1.71-13.89) and 5.91(1.76-22.12) for 40-49 years and age > 50 vs age < 30). The number of confirmed deaths was 13 and the median age at death was 40 years (range, 27 to 85 years). Ten of the deaths (76.9%) were from CRC. Another cause of two cases of death were desmoid tumors (15.4%). Development of cancer on remnant rectal or ileal mucosa after surgery was not observed. The APC mutation testing revealed 23 pathogenic mutations and one likely pathogenic mutation, among which were four novel mutations. The correlation between mutational status and clinical manifestations was investigated. Mutations that could prodict poor prognosis were at codon 1309 which located on mutation cluster region, codon 1465 and codon 1507.

Identification of APC mutations should aid in the diagnosis and counseling of family members in terms of early diagnosis and management of FAP.

Prophylactic surgical options for familial adenomatous polyposis (FAP) are either colectomy and ileorectal anastomosis (IRA) or proctocolectomy and ileal pouch-anal anastomosis (IPAA). The aim of this study was to analyse the short-term and long-term outcomes of these two operative techniques. All patients with FAP in Finland have been prospectively recorded in a database since 1963 were retrospectively reviewed in this analysis. Altogether 140 (61%) colectomies with IRA and 88 (39%) proctocolectomies with IPAA have been performed. Complications occurred in 28 (21%) patients after IRA and in 26 (30%) patients after IPAA. There were 15 (11%) severe complications for IRA and 5 (6%) for IPAA. Twenty-one (15%) patients of the IRA group ended up in conventional ileostomy whereas 3 (3.4%) patients of the IPAA group had their ileal reservoir converted to an ileostomy (p = 0.01). Cumulative survival for IRA was lower than for the IPAA (p = 0.03), but if accounting only for operations made after the IPAA era had commenced, there was no significant difference. IPAA was associated with improved long-term survival without an increase in postoperative complications. The risk of death after colectomy and IRA seemed to be predominantly related to the remaining risk of rectal cancer. Therefore, we favour proctocolectomy with IPAA as the prophylactic surgical procedure for FAP with intermediate or severe polyposis.

We aimed to evaluate the long-term risk of cancer in the rectal remnant in patients with familial adenomatous polyposis after ileorectal anastomosis.

Cumulative incidence and clinicopathological characteristics of cancer in the rectal remnant were retrospectively investigated in 27 patients with familial adenomatous polyposis who had undergone ileorectal anastomosis.

During the follow-up period ranging from 3.0 to 35.0 years (median, 21.1 years), cancer in the rectal remnant developed in 10 patients. Cumulative risk of cancer in the rectal remnant 30 years after surgery was 57%. Five patients had metastases and three patients died of cancer in the rectal remnant after proctectomy. There was a trend towards a higher incidence of cancer in the rectal remnant in patients with small-intestinal adenoma and congenital hypertrophy of the retinal pigment epithelium. Multivariate analysis revealed that the ocular lesion was an independent risk factor associated with cancer in the rectal remnant.

Subtotal colectomy with ileorectal anastomosis does not seem to be an appropriate prophylactic surgery in patients with familial adenomatous polyposis.

Hereditary factors are involved in the development of a substantial proportion of all cases of colorectal cancer. Inherited forms of colorectal cancer are usually subdivided into polyposis syndromes characterized by the development of multiple colorectal polyps and nonpolyposis syndromes characterized by the development of few or no polyps. Timely identification of hereditary colorectal cancer syndromes is vital because patient participation in early detection programmes prevents premature death due to cancer. Polyposis syndromes are fairly easy to recognize, but some patients might have characteristics that overlap with other clinically defined syndromes. Comprehensive analysis of the genes known to be associated with polyposis syndromes helps to establish the final diagnosis in these patients. Recognizing Lynch syndrome is more difficult than other polyposis syndromes owing to the absence of pathognomonic features. Most investigators therefore recommend performing systematic molecular analysis of all newly diagnosed colorectal cancer using immunohistochemical methods. The implementation in clinical practice of new high-throughput methods for molecular analysis might further increase the identification of individuals at risk of hereditary colorectal cancer. This Review describes the clinical management of the various hereditary colorectal cancer syndromes and demonstrates the advantage of using a classification based on the underlying gene defects.

This guideline presents recommendations for the management of patients with hereditary gastrointestinal cancer syndromes. The initial assessment is the collection of a family history of cancers and premalignant gastrointestinal conditions and should provide enough information to develop a preliminary determination of the risk of a familial predisposition to cancer. Age at diagnosis and lineage (maternal and/or paternal) should be documented for all diagnoses, especially in first- and second-degree relatives. When indicated, genetic testing for a germline mutation should be done on the most informative candidate(s) identified through the family history evaluation and/or tumor analysis to confirm a diagnosis and allow for predictive testing of at-risk relatives. Genetic testing should be conducted in the context of pre- and post-test genetic counseling to ensure the patient's informed decision making. Patients who meet clinical criteria for a syndrome as well as those with identified pathogenic germline mutations should receive appropriate surveillance measures in order to minimize their overall risk of developing syndrome-specific cancers. This guideline specifically discusses genetic testing and management of Lynch syndrome, familial adenomatous polyposis (FAP), attenuated familial adenomatous polyposis (AFAP), MUTYH-associated polyposis (MAP), Peutz-Jeghers syndrome, juvenile polyposis syndrome, Cowden syndrome, serrated (hyperplastic) polyposis syndrome, hereditary pancreatic cancer, and hereditary gastric cancer.

The aim of our retrospective study was to review the outcome of patients undergoing colectomy with ileorectal anastomosis (IRA) due to familial adenomatous polyposis (FAP) in Finland during the last 50 years.

The cumulative risk of rectal cancer and the rate of anus preservation were analyzed. A total of 140 FAP patients with previous colectomy combined with ileorectal anastomosis were included. Kaplan-Meier analysis was performed to evaluate cumulative risks.

Secondary proctectomy was performed for 39 (28 %) of 140 patients. The cumulative risk of secondary proctectomy was 53 % at 30 years after colectomy with IRA. A total of 17 (44 %) secondary proctectomies were performed due to cancer or suspicion of cancer, and another 17 (44 %) secondary proctectomies were performed due to uncontrollable rectal polyposis. During our study, the anus preservation rate in secondary proctectomies was 49 %. The cumulative risk of rectal cancer was 24 % at 30 years after colectomy with IRA. Therefore, the cumulative rectal cancer mortality 30 years after colectomy with IRA was 9 %.

Proctocolectomy and ileal pouch-anal anastomosis (IPAA) should be favored as a primary operation for patients not having technical or medical contraindications for it because colectomy with IRA carried a rectal cancer risk of 13 % with a mortality of 7 % during our study, and because IPAA is likely to succeed better at earlier phase of the disease. Patients with attenuated FAP had no rectal cancer in our study, and they may form a group where IRA should still be the first choice as an exception.

Attenuated familial adenomatous polyposis (AFAP) is a variant of familial adenomatous polyposis with fewer than one hundred colorectal polyps and a later age of onset of the cancer. Here, we report two cases of AFAP within family members. Each patient demonstrated the same novel germ line mutation in exon 15 of the adenomatous polyposis coli (APC) gene and was successfully managed with sulindac after refusal to perform colectomy: a 23-year-old man with incidentally diagnosed gastric adenoma and fundic gland polyps underwent colonoscopy, and fewer than 100 colorectal polyps were found; a 48-year-old woman who happened to be the mother of the 23-year-old man also showed fewer than 100 colorectal polyps on colonoscopy. Genetic analysis revealed a novel frameshift mutation in exon 15 of the APC gene. The deletion of adenine-guanine with the insertion of thymine in c.3833-3834 resulted in the formation of stop codon 1,287 in both patients. The patients were treated with sulindac due to their refusal to undergo colectomy. The annual follow-up upper endoscopy and colonoscopy in the following 2 years revealed significant regression of the colorectal polyps in both patients.

Attenuated familial adenomatous polyposis (AFAP) is characterized by the presence of 10-99 colorectal adenomas. The disease may be associated with mutations in either APC or MUTYH genes. We purposed to evaluate the contribution of adenomatous polyposis coli (APC) and MutY homologue (MUTYH) germline alterations to the AFAP phenotype and to identify genotype/phenotype correlations.

During counselling for familial adenomatous polyposis (FAP), 91 probands (and 107 affected individuals) who met the criteria of AFAP were identified. Eighty-two families were screened for constitutional mutations of the APC and MUTYH genes.

MUTYH mutations were detected in 21 families (25.6 % of the 82 tested), and APC mutations in 7 (8.5 %). Overall, constitutional alterations were found in 34.1 % of the probands. Patients with APC mutations were younger at cancer onset and had a higher mean number of polyps (48.5 ± 33.0 in APC+ individuals vs. 35.7 ± 24.9 in MUTYH+ individuals, and 33.2 ± 18.4 in the "no mutation" group). Clinical features rendered the "no mutation" group closer to MUTYH+ than to the APC+ group. Colorectal cancer at diagnosis was detected in 40 % of AFAP individuals.

AFAP is a new clinical entity with its frequency in the general population still undefined. The number of adenomas varies greatly, with an average of 30-40 lesions. The molecular basis of AFAP can be established in approximately 1/3 of the patients. Both MUTYH and APC genes are implicated in AFAP, though the role of MUTYH is of considerably greater relevance.

Surgical management of familial adenomatous polyposis (FAP) is complex and requires both sound judgment and technical skills. Because colorectal cancer risk approaches 100%, prophylactic colorectal surgery remains a cornerstone of management. Both patient factors and disease characteristics influence surgical decision-making regarding the timing of prophylactic surgery, the extent of resection, and types of reconstruction. Making appropriate choices can be challenging and there is continued debate regarding optimal strategies. This chapter reviews the controversies in colorectal surgery for FAP.

Benign skin tumors such as lipomas, fibromas, and epidermal cysts are among the extracolonic manifestations of familial adenomatous polyposis (FAP). Readily detectable by inspection, they could serve as presymptomatic diagnostic markers to identify FAP patients. We therefore prospectively determined the prevalence of cutaneous lesions in genetically confirmed adenomatous polyposis coli (APC) mutation carriers and assessed their potential usefulness in the identification of FAP patients.

Whole-skin examination was performed in 56 adult APC mutation carriers, compared with a control group (n = 116). In addition, FAP patients were investigated for the presence of congenital hypertrophy of the retinal pigment epithelium (CHRPE), an established clinical marker for FAP, and a detailed review of medical records was performed.

Nearly half of all FAP patients (48.2%) had at least one FAP-associated skin lesion, compared with one third (34.5%) of controls. Only multiple lipomas and combined skin lesions were significantly more prevalent in APC mutation carriers. CHRPE was observed in 22 (43.1%) of 51 FAP patients, including 14 (37.8%) of 37 individuals with APC mutations outside the CHRPE-associated region between codons 311 and 1465.

Despite a significantly higher prevalence of multiple lipomas, occurring at younger age, and combined skin lesions in APC mutation carriers, the low diagnostic sensitivity of FAP-associated skin lesions precludes their use as markers for FAP in clinical practice. Based on our findings, the common CHRPE-associated region should be extended to APC codons 148-2043.

Adenomatous polyps are found on screening colonoscopy in 22.5% to 58.2% of the adult population and therefore represent a common problem. Patients with multiple adenomatous polyps are of unique interest because a proportion of these patients have an inheritable form of colorectal cancer. This article discusses the history and clinical features, genetic testing, surveillance, and treatments for the condition.

Familial Adenomatous Polyposis (FAP) is a hereditary disorder with multiple colorectal polyps that exhibit an almost inevitable risk of colorectal cancer (CRC) in untreated patients.

To evaluate clinical features related to CRC risk at diagnosis.

Charts from 88 patients were reviewed to collect information regarding age, family history, symptoms, polyposis severity and association with CRC.

41 men (46.6%) and 47 women (53.4%) were assisted. CRC was detected in 53 patients (60.2%), with a frequency of 9.1% under 20 years, 58% between 21-40 and 85% over 41 years of age. Average age of patients without CRC was lower at treatment (29.5 vs. 40.0 years; p=0.001). Family history was reported by 58 patients (65.9%), whose average age did not differ from those who didn't report it (33.4 vs. 34.4; p=0.17). Asymptomatic patients comprised 10.2% of the total; in this group, CRC incidence was much lower when compared to those presenting symptoms (1.1% vs. 65.8%; p=0.001). Patients without CRC presented a shorter length of symptoms (15.2 vs. 26.4 months; p=0.03) and less frequent weight loss (11.4% vs. 33.9%; p=0.01). At colonoscopy, polyposis was classified as attenuated in 12 patients (14.3%), who presented greater average age (48.2 vs. 33.3 years; p=0.02) and equal CRC incidence (58.3% vs. 58.3%; p=0.6) when compared to those with classic polyposis.

The risk of CRC in FAP patients 1) increases significantly after the second decade; 2) is associated with higher age, weight loss, presence and duration of simptomatology; 3) is similar in patients with attenuated or classic phenotype.