TY - JOUR
T1 - Geographic variation in breast cancer incidence rates in a cohort of u.S. Women
AU - Laden, Francine
AU - Spiegelman, Donna
AU - Neas, Lucas M.
AU - Colditz, Graham A.
AU - Hankinson, Susan E.
AU - Manson, Jo Ann E.
AU - Byrne, Celia
AU - Rosner, Bernard A.
AU - Speizer, Frank E.
AU - Hunter, David J.
PY - 1997/9/17
Y1 - 1997/9/17
N2 - Background: Breast cancer mortality and incidence rates vary by geographic region in the United States. Previous analytic studies have measured mortality, not incidence, and have used regional prevalences to control for geographic variation in risk factors rather than adjusting for risk factors measured at the level of the individual. We prospectively evaluated regional variation in breast cancer incidence rates in the Nurses' Health Study and assessed the influence of breast cancer risk factors measured at the individual level. Methods: The Nurses' Health Study cohort was established in 1976 when 121 700 female nurses aged 30-55 years living in 11 U.S. states were enrolled. These states represent all four regions of the continental United States. We identified 3603 incident cases of invasive breast cancer through 1992 (1794565 person-years of follow-up). We calculated relative risks (RRs) adjusted for age and for age and established risk factors (i.e., multivariate-adjusted analysis), comparing California, the Northeast, and the Midwest with the South. Results: For premenopausal women, there was little evidence of regional variation in breast cancer incidence rates, either in age-adjusted or in multivariate-adjusted analyses. For postmenopausal women in California, age-adjusted risk was modestly elevated (RR = 1.24; 95% confidence interval [CI] = 1.05-1.47); after adjusting for age and for established risk factors, the excess rate in California was attenuated by 25% (RR = 1.18; 95% CI = 1.00-1.40). No excess of breast cancer incidence was observed for postmeno pausal women in either the Northeast or the Midwest. Conclusions: Little regional variation in age-adjusted breast cancer incidence rates was observed, with the exception of a modest excess for postmenopausal women in California. Adjustment for differences in the distribution of established risk factors explained some of the excess risk in California.
AB - Background: Breast cancer mortality and incidence rates vary by geographic region in the United States. Previous analytic studies have measured mortality, not incidence, and have used regional prevalences to control for geographic variation in risk factors rather than adjusting for risk factors measured at the level of the individual. We prospectively evaluated regional variation in breast cancer incidence rates in the Nurses' Health Study and assessed the influence of breast cancer risk factors measured at the individual level. Methods: The Nurses' Health Study cohort was established in 1976 when 121 700 female nurses aged 30-55 years living in 11 U.S. states were enrolled. These states represent all four regions of the continental United States. We identified 3603 incident cases of invasive breast cancer through 1992 (1794565 person-years of follow-up). We calculated relative risks (RRs) adjusted for age and for age and established risk factors (i.e., multivariate-adjusted analysis), comparing California, the Northeast, and the Midwest with the South. Results: For premenopausal women, there was little evidence of regional variation in breast cancer incidence rates, either in age-adjusted or in multivariate-adjusted analyses. For postmenopausal women in California, age-adjusted risk was modestly elevated (RR = 1.24; 95% confidence interval [CI] = 1.05-1.47); after adjusting for age and for established risk factors, the excess rate in California was attenuated by 25% (RR = 1.18; 95% CI = 1.00-1.40). No excess of breast cancer incidence was observed for postmeno pausal women in either the Northeast or the Midwest. Conclusions: Little regional variation in age-adjusted breast cancer incidence rates was observed, with the exception of a modest excess for postmenopausal women in California. Adjustment for differences in the distribution of established risk factors explained some of the excess risk in California.
UR - http://www.scopus.com/inward/record.url?scp=0030870772&partnerID=8YFLogxK
U2 - 10.1093/jnci/89.18.1373
DO - 10.1093/jnci/89.18.1373
M3 - Article
AN - SCOPUS:0030870772
SN - 0027-8874
VL - 89
SP - 1373
EP - 1378
JO - Journal of the National Cancer Institute
JF - Journal of the National Cancer Institute
IS - 18
ER -