Detection rate and risk factors of colorectal adenoma in high-altitude population: A cross-sectional study

Abstract

BACKGROUND

The epidemiology of colorectal cancer (CRC) varies significantly, with an increasing incidence in China. The Xizang Autonomous Region has the lowest CRC mortality nationally, offering a unique natural experiment to investigate carcinogenesis. As most CRCs develop via the adenoma-carcinoma sequence, characterizing the prevalence of its precursor lesion, colorectal adenoma (CRA), is essential for understanding this disparity.

AIM

To characterize the detection rates and risk factors for colorectal lesions in the high-altitude population of Xizang Autonomous Region.

METHODS

In this cross-sectional study, 1154 Tibetans undergoing high-definition colonoscopy were enrolled. Univariate and multivariate logistic regression were conducted to analyze the risk factors for CRA. Data were collected via questionnaire, and the China Sporadic Colorectal Cancer Risk Score and Asia-Pacific Colorectal Screening (APCS) score were calculated. A control group from low altitude was established using a 1:2 case-control matching protocol based on age, sex, body mass index (BMI), and first-degree family history of CRC, and detection rates were compared.

RESULTS

The detection rates in the Xizang Autonomous Region cohort were 7.7% for CRA (n = 89) and 1.6% for CRC (n = 18). Univariate analysis showed that CRA was associated with advanced age, male sex, higher BMI, and higher risk tiers on both the China and APCS scores. However, multivariate logistic regression confirmed only advanced age (OR = 1.035, 95%CI: 1.019-1.052, P < 0.001) and male sex (OR = 2.161, 95%CI: 1.337-3.492, P = 0.002) as independent risk factors. In the comparative analysis, the Xizang CRA detection rate was significantly lower than that in the matched Beijing cohort (7.7% vs 22.8%, P < 0.001). No significant difference was found in CRC detection rates (1.6% vs 1.3%, P = 0.626).

CONCLUSION

The prevalence of CRA in the high-altitude population was significantly lower. Advanced age and male sex remain independent risk factors for CRA in Xizang Autonomous Region.

Key Words: High altitude; Xizang Autonomous Region; Colorectal adenoma; Colorectal cancer; Detection rate

Core Tip: In this cross-sectional study of 1154 Tibetans, the colorectal adenoma (CRA) detection rate in the high-altitude Xizang Autonomous Region population was 7.7%. This was significantly lower than the 22.8% rate found in a rigorously matched low-altitude Beijing cohort. Advanced age and male sex were identified as the only independent risk factors for CRA in the Xizang Autonomous Region group.

INTRODUCTION

Colorectal cancer (CRC) is one of the most common malignant tumors worldwide, with incidence and mortality rates continuing to rise, posing a severe threat to human health and life[1,2]. In recent years, as lifestyles and dietary habits have shifted, the incidence of CRC in China has shown an upward trend, particularly in large cities and coastal areas[3,4]. The majority of CRCs develop via the adenoma-carcinoma sequence, establishing colorectal adenoma (CRA) as the primary precancerous lesion. Endoscopy is recognized as the most effective modality for digestive system cancer prevention, not merely for early cancer detection but, more critically, for the identification and removal of CRA, thereby interrupting their potential progression to malignancy[5].

Variations in environmental factors, lifestyle, and genetic background across different regions may lead to significant disparities in the risk of developing CRA[6,7]. It was analyzed that the cause-specific mortality in China based on global burden of disease data and found that the age-standardized death rate for CRC in the Xizang Autonomous Region was the lowest in China. Xizang Autonomous Region is located on the high-altitude plateau and has a unique population structure, lifestyle, and environment[8-10]. Investigating the detection rates and associated risk factors for CRA via colonoscopy in this region is therefore essential for understanding the epidemiology of these key precursor lesions. This low-incidence setting presents a unique natural experiment. Investigating the epidemiology of CRA in this population is therefore essential for potentially uncovering protective factors or distinct pathogenic pathways that are less apparent in high-risk populations. Unique environmental conditions, such as chronic hypoxia, high levels of ultraviolet radiation, and traditional dietary habits, may modulate the pathogenesis of CRA in ways that differ significantly from low-altitude areas in China[11]. Therefore, further research into the prevalence of colorectal lesions in Xizang Autonomous Region and comparisons with other regions could not only enrich the epidemiological data for this area but also provide a scientific basis for targeted CRC prevention in China.

Therefore, this study aimed to characterize the prevalence and risk factors of colorectal lesions including CRA and CRC in the high-altitude population of Xizang Autonomous Region using both univariate and multivariate analyses of colonoscopy screening data. Additionally, a comparative analysis of the detection rates of colorectal lesions between Xizang Autonomous Region and Beijing was performed to quantify these regional disparities. By elucidating the distinct risk profile of a population with naturally low CRC mortality, this research seeks to provide novel insights and generate new hypotheses for the primary prevention of CRC applicable to the broader Chinese population.

MATERIALS AND METHODS

Population

This cross-sectional study was conducted using prospective data. We prospectively enrolled consecutive Tibetan patients aged ≥ 18 years who were scheduled for colonoscopy at the Department of Gastroenterology, the People's Hospital of Xizang Autonomous Region between January 2024 and October 2024. The study protocol was approved by the Ethics Committee of the People's Hospital of Xizang Autonomous Region (Approval No. ME-TBHP-24-KJ-050). After providing written informed consent, each participant was invited to complete a structured questionnaire administered by trained staff to collect data on demographic information and lifestyle habits. This was completed prior to colonoscopy.

Inclusion criteria for the study were: (1) Age ≥ 18 years; and (2) Completion of the questionnaire and the colonoscopy procedure. We excluded individuals with: (1) A personal history of CRC or other malignancies; (2) A diagnosis of hereditary CRC, such as Lynch syndrome; (3) A known hereditary polyposis syndrome, such as familial adenomatous polyposis; (4) Contraindications for colonoscopy; or (5) Inability to provide informed consent or complete the questionnaire.

To contextualize the findings from the high-altitude cohort, a comparative control group was established from individuals undergoing colonoscopy at Peking Union Medical College Hospital (PUMCH), a major tertiary center in Beijing representing a low-altitude, urban population. A stringent 1:2 case-control matching protocol was implemented. Matching was precisely executed based on four key confounding variables: Sex, age, body mass index (BMI), and a documented first-degree family history of CRC. To achieve robust baseline comparability, matching for sex and family history was exact, while age and BMI were matched using a sequential selection process within predefined tolerances to minimize residual confounding. In the event that suitable matched controls could not be identified for cases, these cases were excluded from the comparative analysis cohort. Using this rigorous procedure, all 1154 individuals in the Xizang Autonomous Region cohort were successfully matched with corresponding individuals from the PUMCH cohort, resulting in a comparative analysis cohort of 1154 Xizang Autonomous Region participants and 2308 Beijing controls. Thus, no participants were excluded from the comparative analysis.

Colonoscopy procedure

To ensure procedural consistency and data comparability between the Xizang Autonomous Region and Beijing cohorts, standardized protocols were implemented at both institutions. Prior to the procedure, all participants received detailed verbal and written instructions for bowel cleansing and consumed a standard, split-dose regimen of a polyethylene glycol-based electrolyte solution. The quality of the bowel preparation was systematically evaluated by the endoscopist using the Boston Bowel Preparation Scale (BBPS). To ensure high-quality mucosal visualization in both cohorts, only examinations with an adequate cleansing level (total BBPS score ≥ 6) were included in the final analysis. All colonoscopies were performed using high-definition video colonoscopes by board-certified gastroenterologists with ≥ 5 years of colonoscopy experience. A minimum withdrawal time of 6 minutes was standard practice for negative colonoscopies at both centers. During withdrawal, the location, size, and morphology of any detected lesions were meticulously documented. Polyp size was estimated using open biopsy forceps as a reference. All identified polyps were resected using standard techniques, and all retrieved specimens were sent for histopathological evaluation by experienced pathologists at each respective institution.

Data collection and management

Prior to colonoscopy, all participants’ data were collected prospectively by trained staff using a single, comprehensive questionnaire. This instrument captured a wide range of information on both demographic and social characteristics, including age, sex, marital status, ethnicity, highest education level, and occupation. Geographic data, specifically long-term place of residence and its corresponding altitude, were also recorded. Anthropometric measurements of height and weight were recorded to calculate BMI. The questionnaire also documented key clinical and lifestyle factors, including self-reported history of hypertension, diabetes mellitus, previous abdominal surgery, and smoking status, which was defined as ever-smoker vs never-smoker. A family history of CRC was considered positive if a participant reported at least one first-degree relative with the disease. Two validated risk stratification scores, the China Sporadic Colorectal Cancer Risk Score and the Asia-Pacific Colorectal Screening (APCS) score (Supplementary Tables 1 and 2), were calculated for each participant to stratify their a priori risk according to the established methodologies[12].

Data management followed a strict workflow. To address follow-up data management, a standardized protocol was used to track and match histopathological results with endoscopic findings. All distinct data streams—questionnaire responses, endoscopic reports, and pathological records—were integrated into a dedicated database. To ensure rigorous data quality control and consistency across the two centers, identical standard operating procedures were enforced, including the use of high-definition colonoscopy, adequate bowel preparation, and a minimum withdrawal time of 6 minutes. All key data underwent independent double-checking and logic verification by two researchers prior to statistical analysis.

Statistical analysis

Statistical analysis was conducted using IBM SPSS 26.0 (Armonk, NY, United States) and R version 4.2.2 (the R Foundation for Statistical Computing, Vienna, Austria). Continuous variables following a normal distribution are expressed as mean ± SD and were tested for normality using the Shapiro-Wilk test. Independent sample t tests were used for between-group comparisons, paired sample t tests for within-group comparisons, and one-way analysis of variance for comparing normally distributed continuous variables across multiple groups. Categorical data are presented as frequencies and percentages and were analyzed using the χ² test or Fisher’s exact test. Variables with significant results in univariate analysis were further examined using multivariate logistic regression. Linear trend analysis was conducted using GraphPad Prism 9 (San Diego, CA, United States). A P value < 0.05 was considered statistically significant.

RESULTS

Patient characteristics

A total of 1154 participants of Tibetan ethnicity were included in the study. CRA was detected in 89 (7.7%) and CRC in 18 (1.6%). The mean age of the population was 46.49 ± 14.19 years. The gender distribution was 50.1% female and 49.9% male. The average BMI was 23.35 ± 4.18 kg/m². Participants were from various cities in the Xizang Autonomous Region, including Lhasa 376 (32.6%), Shannan 95 (8.2%), Nyingchi 42 (3.6%), Shigatse 227 (19.7%), Chamdo 120 (10.4%), Nagqu 267 (23.1%), and Ngari 27 (2.3%). The altitude distribution of participants' residential areas was as follows: 2000-3000 m in 57 (4.9%), 3000-4000 m in 426 (36.9%), 4000-5000 m in 654 (56.7%), and > 5000 m in 17 (1.5%). A history of smoking was reported by 170 participants (14.7%). A family history of CRC was present in 95 participants (8.2%). Based on the China Risk Score for Sporadic CRC, 1034 participants (89.6%) were classified as low risk, and 120 (10.4%) as high risk. According to the Asia-Pacific Risk Score for CRC, 531 participants (46.0%) were at average risk, 508 participants (44.0%) at moderate risk, and 115 participants (10.0%) at high risk. Key demographic and clinical characteristics are presented in Supplementary Table 3.

Comparison of characteristics between the colorectal lesion and control groups

Participants were divided into two groups: 89 in the CRA group and 1065 in the healthy group. Univariate comparisons between the two groups were performed (Table 1). With regard to age, the CRA group was significantly older than the healthy group (52.70 ± 13.03 years vs 45.97 ± 14.17 years; P < 0.001). Significant differences in age distribution were observed between the two groups. The detection rate of CRA was significantly different across different age groups (P < 0.01; Supplementary Table 4), and a linear trend test revealed that the detection rate of CRA significantly increased with age (R² = 0.9851, P < 0.01; Figure 1A). The BMI of the CRA group was significantly higher than that of the healthy group (24.91 ± 3.54 kg/m²vs 24.30 ± 4.22 kg/m², P < 0.042). The number of individuals at high risk, according to the China Risk Score for Sporadic CRC and the Asia-Pacific Risk Score for CRC, was significantly higher in the CRA group compared to the healthy group (P < 0.01) and the risk level showed a positive correlation with CRA (Figure 1B). No significant differences were observed between the two groups in terms of city of residence, altitude, smoking history, hypertension, diabetes mellitus, history of abdominal surgery, or family history of CRC (P > 0.05). Patients were also divided into the CRC group (n = 18) and control group (n = 1136) and univariate comparisons were performed (Supplementary Table 5).

Figure 1 Overview of colorectal adenoma detection rate. A: Age-specific colorectal adenoma (CRA) detection rates in the Xizang Autonomous Region population and corresponding linear trend test; B: CRA detection rates among different risk scores in the Xizang Autonomous Region population; C: Comparison of CRA detection rates between the Xizang Autonomous Region and Beijing populations. ^aP < 0.01.

Table 1 Univariate analysis of clinical features in colorectal adenoma patients, n (%).

	Colorectal adenoma group (n = 89)	Healthy group (n = 1065)	Statistic (t/χ²/z)	P value
Age (years)	52.70 ± 13.03	45.97 ± 14.17	-4.294	< 0.001
Age distribution (year)			19.924	< 0.001
< 40	14 (15.7)	387 (36.3)
40-49	21 (23.6)	248 (23.3)
50-59	26 (29.2)	229 (21.5)
≥ 60-69	28 (31.5)	201 (18.9)
Sex			13.383	< 0.001
Male	61 (68.5)	515 (48.4)
Female	28 (31.5)	550 (51.6)
BMI (kg/m2)	24.91 ± 3.54	24.30 ± 4.22	-2.038	0.042
BMI > 24.9 kg/m2			2.521	0.112
No	46 (51.7)	642 (60.3)
Yes	43 (48.3)	423 (39.7)
Residence			2.745	0.840
Lhasa	35 (39.3)	341 (32.0)
Shannan	8 (9.0)	87 (8.2)
Nyingchi	3 (3.4)	39 (3.7)
Shigatse	17 (19.1)	210 (19.7)
Chamdo	8 (9.0)	112 (10.5)
Nagqu	16 (18.0)	251 (23.6)
Ngari	2 (2.2)	25 (2.3)
Altitude of residence (m)			4.236	0.237
2000-3000	1 (1.1)	56 (5.3)
3000-4000	38 (42.7)	388 (36.4)
4000-5000	48 (54.0)	606 (56.9)
> 5000	2 (2.2)	15 (1.4)
Smoking history			3.361	0.067
No	70 (78.7)	914 (85.5)
Yes	19 (21.3)	151 (14.2)
Hypertension			0.010	0.920
No	82 (92.1)	978 (91.8)
Yes	7 (7.9)	87 (8.2)
Diabetes mellitus			0.290	0.590
No	86 (96.6)	1039 (97.6)
Yes	3 (3.4)	26 (2.4)
History of abdominal surgery			0.038	0.846
No	80 (90.0)	964 (90.5)
Yes	8 (9.0)	101 (9.5)
Family history of CRC			0.017	0.896
No	82 (92.1)	977 (91.7)
Yes	7 (7.9)	88 (8.3)
China risk score for sporadic CRC			18.026	< 0.001
Low risk	68 (76.4)	966 (90.7)
High risk	21 (23.6)	99 (9.3)
Asia-Pacific risk score for CRC			15.980	< 0.001
Average risk	27 (30.3)	504 (47.3)
Moderate risk	44 (49.4)	464 (43.6)
High risk	18 (20.2)	97 (9.1)

CRC: Colorectal cancer; BMI: Body mass index.

Multivariate logistic regression analysis of the CRA and healthy groups

Multivariate logistic regression analysis was conducted to predict the independent risk factors for CRA in the population (Table 2). Age (OR = 1.035, 95%CI: 1.019-1.052, P < 0.001) and male sex (OR = 2.161, 95%CI: 1.337-3.492, P = 0.002) were found to be independent risk factors. Other factors, including BMI, altitude, smoking, diabetes mellitus, and family history of CRC, were not significant (P > 0.05).

Table 2 Multivariate logistic regression analysis of variables in colorectal adenoma patients.

Predictor variables	B	SE	Wald	df	P value	OR	95%CI
							Lower	Upper
Age	0.034	0.008	17.782	1	< 0.001	1.035	1.019	1.052
Body mass index	0.036	0.027	1.809	1	0.179	1.037	0.984	1.092
Sex (male)	0.770	0.245	9.904	1	0.002	2.161	1.337	3.492
Altitude (m)			3.942	3	0.268
3000-4000	1.703	1.030	2.733	1	0.098	5.491	0.729	41.348
4000-5000	1.511	1.029	2.155	1	0.142	4.530	0.603	34.035
> 5000	2.279	1.275	3.196	1	0.074	9.768	0.803	118.826
Smoking history (yes)	0.455	0.291	2.440	1	0.118	1.576	0.890	2.790
Diabetes mellitus (yes)	-0.189	0.639	0.087	1	0.767	0.828	0.237	2.895
Family history of colorectal cancer (yes)	0.010	0.422	0.001	1	0.981	1.010	0.422	2.308

B: Regression coefficient; SE: Standard error; Wald: Wald χ² test; df: Degrees of freedom.

Subgroup analysis of CRA in different altitude regions

To investigate CRA in different high-altitude regions, we conducted subgroup analyses on populations residing at 3000-4000 m and 4000-5000 m. Univariate analysis and multivariate logistic regression were performed for each subgroup (Supplementary Tables 6-9). In the population residing at 3000-4000 m, age was identified as an independent risk factor (OR = 1.042, 95%CI: 1.017-1.068, P < 0.001). For the population residing at 4000-5000 m, age (OR = 1.025, 95%CI: 1.003-1.048, P = 0.024) and male sex (OR = 3.249, 95%CI: 1.609-6.563, P = 0.001) were independent risk factors.

Comparative analysis of colorectal lesion detection rates between Xizang Autonomous Region and Beijing populations

To investigate potential differences in colorectal lesion detection rates influenced by geographical and altitude factors, we conducted a 1:2 matching analysis between Tibetan patients and those from the PUMCH cohort, matched by age, sex, BMI, and family history of CRC. The detection rate of CRA was significantly lower among Tibetan patients compared to the Beijing group (7.7% vs 22.8%, P < 0.001; Table 3 and Figure 1C). The detection rate of CRC showed no significant difference between the two groups (1.6% vs 1.3%, P = 0.626; Supplementary Table 10).

Table 3 Comparison of colorectal adenoma detection rates between the Beijing and Xizang Autonomous Region populations, n (%).

	Study population (n = 3462)	Beijing population (n = 2308)	Xizang Autonomous Region population (n = 1154)	Statistic (χ2)	P value
Groups				120.64	< 0.001
Healthy group	2847 (82.2)	1782 (77.2)	1065 (92.3)
Colorectal adenoma group	615 (17.8)	526 (22.8)	89 (7.7)

DISCUSSION

This study presents the first systematic epidemiological investigation of colorectal lesions in the high-altitude population of Xizang Autonomous Region, coupled with a direct comparison with a low-altitude urban population. Our findings confirm that in this unique population, established risk factors such as advanced age and male sex are also significant predictors for the development of CRA. Comparative analysis revealed that the CRA detection rate in the Xizang Autonomous Region cohort was significantly lower than in the Beijing cohort, with rigorous matching for key confounding variables including age, sex, BMI, and family history. This reveals a distinct epidemiological profile for colorectal neoplasia in the Xizang Autonomous Region population and strongly suggests that unique factors associated with high-altitude living may confer protection during the early stages of colorectal carcinogenesis; namely at the adenoma formation stage.

The analysis of risk factors within our Xizang Autonomous Region cohort provides critical insights into the characteristics of CRA development in this region. Our results identified advanced age as a potent, independent risk factor for CRA. This is consistent with the vast body of research on colorectal neoplasia worldwide, reaffirming the universal role of cellular senescence and cumulative exposure to carcinogens in the pathogenesis of CRA, regardless of geography or ethnicity[13-15]. Similarly, our study identified male sex as another significant independent risk factor. This aligns with numerous epidemiological reports that consistently document a higher detection rate of adenomas in men, potentially attributable to hormonal differences or lifestyle-related exposures more prevalent in men[16]. However, other conventional risk factors such as BMI and smoking history did not retain independent statistical significance in the multivariate regression model. This suggests that the contribution of these factors to CRA risk is minor in this specific Xizang Autonomous Region population, or their effects are overshadowed by the more dominant influence of age and sex. It is of practical importance that our findings validated the clinical utility of the China Sporadic Colorectal Cancer Risk Score and the APCS score within the Xizang Autonomous Region population. Our data showed that the detection rate of CRA increased significantly with higher risk tiers on both scores, demonstrating a clear positive relationship. This confirms that even in a population with a lower overall CRA incidence, these composite scoring systems, built upon the integration of common risk factors, serve as simple yet effective noninvasive tools for identifying individuals at higher risk who should be prioritized for colonoscopy. This provides an evidence-based foundation for implementing targeted screening strategies in the resource-constrained settings of high-altitude regions.

This study also revealed that the detection rate of CRA in the Xizang Autonomous Region cohort (7.7%) was substantially lower than that in the Beijing cohort (22.8%). This disparity was identified after a rigorous 1:2 matching protocol for age, sex, BMI, and family history, which suggests the existence of region-specific protective factors. Potential reasons for the reduced incidence of CRA could include adaptive genetic changes in the long-term high-altitude population, as well as alterations in the gut microbiome resulting from the unique high-altitude environment and diet, which is worthy of future in-depth investigation[17]. Concurrently, we found no significant difference in the detection rates of CRC between the two groups. We posit that this phenomenon can be reasonably explained from a clinical practice perspective. In Xizang Autonomous Region, patients are more likely to undergo colonoscopy due to the presence of significant symptoms. In contrast, the widespread use of screening colonoscopy in Beijing allows for the detection and removal of lesions at the precancerous adenoma stage. Therefore, the CRC detection rates may be a consequence of selection bias stemming from different patterns of clinical presentation. It is also possible that with the low absolute number of CRC cases, our study was statistically underpowered to detect a potentially smaller difference in the true incidence rates between the two regions.

The low detection rate of CRA in high-altitude populations presents a compelling area for further investigation. It was reported that the age-standardized mortality rate of CRC in the Xizang Autonomous Region is the lowest in China. Similarly, it was reported that the incidence ranking of CRC in Xizang Autonomous Region is significantly lower than in other provinces. These epidemiological findings suggest a reduced burden of colorectal neoplasia, potentially associated with unique protective factors. Genetic variations resulting from long-term adaptation to high-altitude environments may be one contributory factor. Environmental influences are also likely to play an important role. Zhao et al[18] identified distinctive features in the gut microbiota of high-altitude populations and demonstrated that microbial metabolites such as butyrate are functionally involved in altitude adaptation. Dietary habits may enhance these protective effects. The Xizang Autonomous Region population regularly consumes highland barley products such as tsampa and has a long-standing tradition of eating yak milk yogurt, which is rich in probiotics[19,20]. These dietary patterns may contribute to gut health and help reduce the risk of adenoma development. Collectively, these genetic, microbial, and dietary characteristics may underlie the low prevalence of CRAs observed in high-altitude populations.

Despite these important findings, this study had several limitations that warrant consideration. First and foremost, the study was constrained by unmeasured confounding variables that may have influenced the observed disparity in CRA prevalence. Our matching protocol controlled for key demographic factors but did not extend to lifestyle and environmental information. Specifically, data on diet, physical activity, alcohol consumption, and medication use were not collected. The traditional Tibetan diet, which differs substantially from urban dietary patterns, is a plausible protective factor and represents a significant potential confounder. The inability to adjust for these variables in our models means we cannot exclude the possibility of residual confounding. Consequently, our hypotheses regarding the mechanisms underlying the lower CRA prevalence in Xizang Autonomous Region remain speculative and require direct validation in future research integrating detailed biological and environmental data. Second, the study design introduced potential for selection bias and limited causal inference. This was a cross-sectional study with participants recruited from single tertiary medical centers, not a population-wide screening initiative. Therefore, the health status and healthcare-seeking behaviors of these hospital-attending populations may not be fully representative of the general population in their respective regions. Furthermore, the cross-sectional design inherently demonstrates associations, not definitive causal pathways, which would require prospective, longitudinal studies for confirmation. Finally, while the overall sample size was substantial, the absolute number of CRC cases was low. This limited the statistical power for the comparative analysis of CRC rates between the two cohorts and thus warrants a cautious interpretation of this particular finding.

This study provides the first systematic characterization of the epidemiology of colorectal lesions in the high-altitude population of Xizang Autonomous Region, and confirms the applicability of traditional risk factors such as age and sex, as well as existing risk scores, in this unique population. Using a rigorously matched comparative analysis with a low-altitude urban population, this study clearly revealed a significantly lower detection rate of CRA in the Xizang Autonomous Region population. This significant disparity in precancerous lesions highlights a potentially unique pattern in the development and progression of colorectal tumors within this population. Future research should focus on conducting larger-scale, multicenter, prospective cohort studies, integrating detailed data on diet and environmental exposures, with the aim of uncovering the specific protective mechanisms behind this disparity. In the long term, elucidating these intrinsic protective factors is not only important for optimizing CRC screening and prevention strategies in China's high-altitude regions but could also potentially provide new perspectives and targets for the primary prevention of CRC worldwide.

CONCLUSION

This study of 1154 individuals from a high-altitude population found detection rates of 7.7% for CRA and 1.6% for CRC, and identified advanced age and male sex as independent risk factors for CRA. In comparison with a rigorously matched low-altitude urban cohort, the CRA detection rate in the Xizang Autonomous Region population was significantly lower. This study is limited by the recruitment of Tibetans from a single tertiary hospital in Xizang Autonomous Region, which may have introduced selection bias and could limit the generalizability of findings to the broader high-altitude population. The research elucidates the epidemiological characteristics of colorectal tumors in this population, providing a key epidemiological basis for future related studies.