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

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.

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

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.

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).

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.