Socioeconomic risk factors for breast cancer: distinguishing individual- and community-level effects.
BACKGROUND
Women are at higher risk of breast cancer if they have higher socioeconomic status (SES) or live in higher SES or urban communities. We examined whether women living in such communities remained at greater risk of breast cancer after controlling for individual education and other known individual-level risk factors.


METHODS
Data were from a population-based, breast cancer case-control study conducted in Wisconsin from 1988 to 1995 (n = 14,667). Data on community SES and urbanicity come from the 1990 census, measured at the census tract and zip code levels. We evaluated relationships between individual- and community-level variables and breast cancer risk using multilevel logistic regression models with random community intercepts.


RESULTS
After controlling for individual education and other individual-level risk factors (age, mammography use, family history of breast cancer, parity, age at first birth, alcohol intake, body mass index, hormone replacement use, oral contraceptive use, and menopausal status), women living in the highest SES communities had greater odds of having breast cancer than women living in the lowest SES communities (1.20; 95% confidence interval = 1.05-1.37). Similarly, the odds were greater for women in urban versus rural communities (1.17; 1.06-1.28).


CONCLUSIONS
Community SES and urbanicity are apparently not simply proxies for individual SES. Future research should examine why living in such communities itself is associated with greater risk of breast cancer.
Robert
Stephanie A
SA
School of Social Work, Center for Demography of Health and Aging, Institute for Research on Poverty, University of Wisconsin-Madison, 53706, USA. sarobert@wisc.edu
Strombom
Indiana
I
Trentham-Dietz
Amy
A
Hampton
John M
JM
McElroy
Jane A
JA
Newcomb
Polly A
PA
Remington
Patrick L
PL
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000191:economics / Q000453:epidemiology*; D016022:Case-Control Studies; D019352:Censuses; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D016015:Logistic Models; D008875:Middle Aged; D012042:Registries; D012111:Residence Characteristics; D012307:Risk Factors; D012423:Rural Health / Q000706:statistics & numerical data; D012923:Social Class; D012959:Socioeconomic Factors; D014504:Urban Health / Q000706:statistics & numerical data*; D014922:Wisconsin / Q000453:epidemiology