Proportion of Breast Cancer Cases in the United States Explained by Well-Established Risk Factors

Background Few estimates of the fraction of cases of breast cancer attributable to recognized risk factors have been published. All estimates are based on selected groups, making their generalizability to the U.S. population uncertain. Purpose Our goal was to estimate the fraction of breast cancer c...

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Bibliographic Details
Published in:JNCI : Journal of the National Cancer Institute 1995-11, Vol.87 (22), p.1681-1685
Main Authors: Madigan, M. Patricia, Ziegler, Regina G., Benichou, Jacques, Byrne, Celia, Hoover, Robert N.
Format: Article
Language:English
Subjects:
Adult
Age Factors
Aged
Biological and medical sciences
Breast cancer
Breast Neoplasms - epidemiology
Breast Neoplasms - etiology
Breast Neoplasms - genetics
Female
Gynecology. Andrology. Obstetrics
Health risk assessment
Humans
Income
Mammary gland diseases
Medical research
Medical sciences
Middle Aged
Parity
Pregnancy
Risk Factors
Tumors
United States - epidemiology
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Summary:Background Few estimates of the fraction of cases of breast cancer attributable to recognized risk factors have been published. All estimates are based on selected groups, making their generalizability to the U.S. population uncertain. Purpose Our goal was to estimate the fraction of breast cancer cases in the United States attributable to well-established risk factors (i.e., later age at first birth, nulliparity, higher family income, and first-degree family history of breast cancer), using data from the first National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study (NHEFS), the survey and follow-up of a probability sample of the U.S. population. Methods From a cohort of 7508 female participants surveyed in the early 1970s, and followed up between 1982 and 1984 and again in 1987, 193 breast cancer cases were accrued for study. We calculated incidence rates, relative risks (RRs), and population attributable risks (PARs) for breast cancer risk factors and extended our results to the U.S. female population by using sample weights from the NHANES I survey. Results Our PAR estimates suggest that later age at first birth and nulliparity accounted for a large fraction of U.S. breast cancer cases, 29.5% (95% confidence interval [CI] = 5.6%–53.3%); higher income contributed 18.9% (95% CI = −4.3% to 42.1%), and family history of breast cancer accounted for 9.1% (95% CI = 3.0%–15.2%). Taken together, these well-established risk factors accounted for approximately 47% (95% CI = 17%–77%) of breast cancer cases in the NHEFS cohort and about 41% (95% CI = 2%–80%) in the U.S. population. Conclusions The RRs for most of these risk factors were modest, but their prevalence as a group was high, leading to estimates that suggest that a substantial proportion of breast cancer cases in the United States are explained by well-established risk factors. Implications Elucidation of the determinants underlying recognized factors and study of other factors that may confer risk or protection are needed in efforts to advance understanding of breast cancer etiology and to aid in devising strategies for prevention. [J Natl Cancer Inst 1987;87:1681–5]
ISSN:0027-8874
1460-2105
DOI:10.1093/jnci/87.22.1681