Menopausal hormone therapy use and risk of invasive colon cancer: the California Teachers Study.
Results from epidemiologic studies of hormone therapy use and colon cancer risk are inconsistent. This question was investigated in the California Teachers Study (1995-2006) among 56,864 perimenopausal or postmenopausal participants under 80 years of age with no prior colorectal cancer by using Cox proportional hazards regression. Incident invasive colon cancer was diagnosed among 442 participants. Baseline-recent hormone therapy users were at 36% lower risk for colon cancer versus baseline-never users (baseline-recent users: relative risk (RR) = 0.64, 95% confidence interval (CI): 0.51, 0.80). Results did not differ by formulation. Estimated risk was lower among baseline-recent hormone therapy users with increasing duration between 5 and 15 years of use (RR = 0.49, 95% CI: 0.35, 0.68), but the trend did not persist in the longest duration group, more than 15 years of use (RR = 0.69, 95% CI: 0.52, 0.92; P(trend) = 0.60). Long-term recreational physical activity, obesity, regular use of nonsteroidal antiinflammatory medications, and daily alcohol intake did not modify these effects; baseline-recent use was more strongly associated with colon cancer risk among women with a family history of colorectal cancer (P(heterogeneity) = 0.04). Baseline-recent hormone therapy use was inversely associated with invasive colon cancer risk among perimenopausal and postmenopausal women in the California Teachers Study.
Delellis Henderson
Katherine
K
Department of Population Sciences, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA 91010, USA. khenderson@coh.org
Duan
Lei
L
Sullivan-Halley
Jane
J
Ma
Huiyan
H
Clarke
Christina A
CA
Neuhausen
Susan L
SL
Templeman
Claire
C
Bernstein
Leslie
L
D000328:Adult; D000886:Anthropometry; D002140:California / Q000453:epidemiology; D003110:Colonic Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000517:prevention & control; D005178:Faculty / Q000706:statistics & numerical data; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D008593:Menopause; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D011795:Surveys and Questionnaires