Biomaterial Database

Estrogen replacement therapy and risk of fatal colon cancer in a prospective cohort of postmenopausal women. 1995

E E Calle, and H L Miracle-McMahill, and M J Thun, and C W Heath

American Cancer Society, Atlanta, GA 30329, USA.

BACKGROUND The results of several recent epidemiologic studies suggest that estrogen replacement therapy (ERT) in postmenopausal women may decrease their risk of subsequently developing colon or colorectal cancer. However, the association is not clear, as other similar studies have failed to show this inverse relationship. OBJECTIVE The present study attempts a more definitive analysis of the relationship between fatal colon cancer and use of ERT among women in a large prospective study of adults in the United States. METHODS Women were selected for study from the 676,526 female participants in Cancer Prevention Study II (CPS-II), a prospective mortality study of about 1.2 million American men and women (from all 50 states, the District of Columbia, and Puerto Rico), begun by the American Cancer Society in 1982. The median age of the female CPS-II participants was 56 years in 1982. Vital status was determined through December 31, 1989; 630,585 participants (93.2%) were still alive and 43,862 (6.5%) had died after 7 years of follow-up. Death certificates were obtained for 96.2% of participants known to have died. At the end of follow-up, 897 colon cancer deaths were observed in a cohort of 422,373 postmenopausal women who were cancer free at study entry. Cox proportional hazards modeling was used to compute rate ratios (RRs) and to adjust for other potential risk factors. The likelihood ratio test (two-sided) was used to determine the statistical significance of the interaction terms. RESULTS Ever use of ERT was associated with significantly decreased risk of fatal colon cancer (RR = 0.71; 95% confidence interval [CI] = 0.61-0.83). The reduction in risk was strongest among current users (RR = 0.55; 95% CI = 0.40-0.76), and there was a significant (P = .0001) trend of decreasing risk with increasing years of use among all users: Users of 1 year or less had an RR of 0.81 (95% CI = 0.63-1.03), while users of 11 years or more had an RR of 0.54 (95% CI = 0.39-0.76). These associations were not altered in multivariate analyses controlling for other risk factors. CONCLUSIONS In our data, estrogen therapy, particularly recent and long-term use, was associated with a substantial decrease in risk of fatal colon cancer. These results were consistent with several published studies suggesting a protective role of exogenous estrogens in the development of colorectal cancer and merit further investigation.

UI	MeSH Term	Description	Entries
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D011446	Prospective Studies	Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.	Prospective Study,Studies, Prospective,Study, Prospective
D003110	Colonic Neoplasms	Tumors or cancer of the COLON.	Cancer of Colon,Colon Adenocarcinoma,Colon Cancer,Cancer of the Colon,Colon Neoplasms,Colonic Cancer,Neoplasms, Colonic,Adenocarcinoma, Colon,Adenocarcinomas, Colon,Cancer, Colon,Cancer, Colonic,Cancers, Colon,Cancers, Colonic,Colon Adenocarcinomas,Colon Cancers,Colon Neoplasm,Colonic Cancers,Colonic Neoplasm,Neoplasm, Colon,Neoplasm, Colonic,Neoplasms, Colon
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000368	Aged	A person 65 years of age or older. For a person older than 79 years, AGED, 80 AND OVER is available.	Elderly
D014481	United States	A country in NORTH AMERICA between CANADA and MEXICO.
D015914	Estrogen Replacement Therapy	The use of hormonal agents with estrogen-like activity in postmenopausal or other estrogen-deficient women to alleviate effects of hormone deficiency, such as vasomotor symptoms, DYSPAREUNIA, and progressive development of OSTEOPOROSIS. This may also include the use of progestational agents in combination therapy.	Hormone Replacement Therapy, Post-Menopausal,Postmenopausal Hormone Replacement Therapy,Replacement Therapy, Estrogen,Estrogen Progestin Combination Therapy,Estrogen Progestin Replacement Therapy,Estrogen Replacement,Replacement, Estrogen,Therapy, Estrogen Replacement,Estrogen Replacement Therapies,Estrogen Replacements,Hormone Replacement Therapy, Post Menopausal,Replacement Therapies, Estrogen,Replacements, Estrogen,Therapies, Estrogen Replacement
D016016	Proportional Hazards Models	Statistical models used in survival analysis that assert that the effect of the study factors on the hazard rate in the study population is multiplicative and does not change over time.	Cox Model,Cox Proportional Hazards Model,Hazard Model,Hazards Model,Hazards Models,Models, Proportional Hazards,Proportional Hazard Model,Proportional Hazards Model,Cox Models,Cox Proportional Hazards Models,Hazard Models,Proportional Hazard Models,Hazard Model, Proportional,Hazard Models, Proportional,Hazards Model, Proportional,Hazards Models, Proportional,Model, Cox,Model, Hazard,Model, Hazards,Model, Proportional Hazard,Model, Proportional Hazards,Models, Cox,Models, Hazard,Models, Hazards,Models, Proportional Hazard
D016017	Odds Ratio	The ratio of two odds. The exposure-odds ratio for case control data is the ratio of the odds in favor of exposure among cases to the odds in favor of exposure among noncases. The disease-odds ratio for a cohort or cross section is the ratio of the odds in favor of disease among the exposed to the odds in favor of disease among the unexposed. The prevalence-odds ratio refers to an odds ratio derived cross-sectionally from studies of prevalent cases.	Cross-Product Ratio,Risk Ratio,Relative Odds,Cross Product Ratio,Cross-Product Ratios,Odds Ratios,Odds, Relative,Ratio, Cross-Product,Ratio, Risk,Ratios, Cross-Product,Ratios, Risk,Risk Ratios