Hormone replacement therapy and colon cancer among members of a health maintenance organization.
We investigated the association between hormone replacement therapy (HRT), primarily conjugated estrogens with or without medroxyprogesterone acetate, and colon cancer risk in a nested case-control study among women ages 55-79 years enrolled in Group Health Cooperative, a health maintenance organization in Washington state. Cases were diagnosed between 1984 and 1993. We selected controls randomly from enrollment files. HRT use was ascertained from a computerized database containing virtually all prescriptions dispensed since 1977. Among subjects with at least 5 years of pharmacy database information before reference date (1 year before diagnosis date), there were 341 cases of incident colon cancer and 1,679 controls. Estrogen use during the 5 years before reference date was not associated with risk of colon cancer [odds ratio (OR) = 0.85 and 95% confidence interval (CI) = 0.57-1.27 for 1-749 estrogen tablets; OR = 0.97 and 95% CI = 0.68-1.40 for > or =750 estrogen tablets]. An analysis including only women with at least 10 years of pharmacy database coverage found no association with use during the 10 years before reference date [OR = 1.07 (95% CI = 0.61-1.86) for 1-749 estrogen tablets; OR = 1.11 (95% CI = 0.69-1.80) for 750 or more estrogen tablets]. These results do not support the hypothesis that recent HRT use substantially reduces risk of colon cancer.
Public Health Sciences, Division, Fred Hutchinson Cancer Research Center, University of Washington, Seattle, USA.
E J
EJ
Jacobs
E
E
White
N S
NS
Weiss
S R
SR
Heckbert
A
A
LaCroix
W E
WE
Barlow
D000230:Adenocarcinoma / Q000453:epidemiology*; D000368:Aged; D003110:Colonic Neoplasms / Q000453:epidemiology*; D016001:Confidence Intervals; D015914:Estrogen Replacement Therapy; D004966:Estrogens, Conjugated (USP) / Q000627:therapeutic use*; D005260:Female; D006279:Health Maintenance Organizations; D006801:Humans; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D014861:Washington / Q000453:epidemiology
D004966:Estrogens, Conjugated (USP)