Menopausal Hormone Therapy Use and Risk of Invasive Colon Cancer: The California Teachers Study

摘要

Results from epidemiologic studies of hormone therapy use and colon cancer risk are inconsistent. This questionnwas investigated in the California Teachers Study (1995–2006) among 56,864 perimenopausal or postmenopausalnparticipants under 80 years of age with no prior colorectal cancer by using Cox proportional hazardsnregression. Incident invasive colon cancer was diagnosed among 442 participants. Baseline-recent hormonentherapy users were at 36% lower risk for colon cancer versus baseline-never users (baseline-recent users: relativenrisk (RR) ?0.64, 95% confidence interval (CI): 0.51, 0.80). Results did not differ by formulation. Estimated risk wasnlower among baseline-recent hormone therapy users with increasing duration between 5 and 15 years of usen(RR ?0.49, 95% CI: 0.35, 0.68), but the trend did not persist in the longest duration group, more than 15 years ofnuse (RR ?0.69, 95% CI: 0.52, 0.92; Ptrend ?0.60). Long-term recreational physical activity, obesity, regular use ofnnonsteroidal antiinflammatory medications, and daily alcohol intake did not modify these effects; baseline-recentnuse was more strongly associated with colon cancer risk among women with a family history of colorectal cancern(Pheterogeneity ?0.04). Baseline-recent hormone therapy use was inversely associated with invasive colon cancernrisk among perimenopausal and postmenopausal women in the California Teachers Study.