Risk factors for colorectal adenomas among immediate family members of patients with colorectal cancer in Taiwan: A case-control study

OBJECTIVES: The incidence of colorectal cancer or adenoma among first-degre e relatives of patients with colorectal cancer is significantly high. Howev er, a well defined screening and surveillance consensus has not been develo ped for these families in Taiwan. We conducted this study to evaluate the c olorectal adenoma prevalence pattern in screened immediate family members i n Taiwan, and to derive implications for future screening programs. METHODS: A total of 234 immediate family members (aged 51.6 +/- 21.5 yr) of 186 patients with colorectal cancer were offered a colonoscopy. Each relat ive examined was then paired with two control subjects for age, sex, and sy mptoms. The prevalence of colorectal adenomas was then compared using multi ple logistic regression analysis. RESULTS: The estimated risk of developing adenomas among immediate family m embers of patients with colorectal cancer was significantly increased (OR = 2.33; 95% CI, 1.43-3.78; p < 0.001). This trend was more striking for men (OR = 2.46; 95% CI, 1.40-4.31; p = 0.001). Immediate family members were at an increased risk for high-risk adenomas (<greater than or equal to>1.0 cm , with a villous component, and/or with severe dysplasia) (OR = 4.5; 95% CI , 1.91-10.60; p = 0.002), and developed adenomas at an earlier age than did controls. Individuals with index cancer relatives diagnosed at <50 yr of a ge or male relatives posed a higher risk of developing colorectal adenomas. CONCLUSIONS: The prevalence of colorectal adenoma in persons with a colorec tal cancer family history in Taiwan is similar to that reported in Western countries. This high-risk population should be offered a screening colonosc opy beginning at 40 yr of age. (C) 2000 by Am. Coll. of Gastroenterology.