Socioeconomic status and breast cancer incidence in California for different race/ethnic groups

Objective: The majority of research on breast cancer risk and socioeconomic status (SES) has been conducted for blacks and whites. This study evaluate s the relationship between SES and breast cancer incidence in California fo r four race/ethnic groups. Methods: Principal component analysis was used to create an SES index using 1990 Census data. Untracted cases were randomly allocated to census block groups within their county of residence. A total of 97,227 female breast ca ncer cases diagnosed in California between 1988 and 1992 were evaluated. In cidence rates and rate ratios (RRs) were estimated and a chi (2) test for t rend across SES levels was performed. Results: SES was positively related to breast cancer incidence, and this ef fect was stronger for Hispanics and Asian/others than for whites and blacks . Adjusting by SES did not eliminate the differences in breast cancer rates among race/ethnic groups. RR differences between the race/ethnic groups we re greatest in the lowest SES category and attenuated with increasing SES. An increasing trend over SES was statistically significant for all race/eth nic groups. Including randomly allocated cases affected RR estimates for wh ite women only. Conclusions: Our results are consistent with similar findings for the Los A ngeles area but differ from previous results for the San Francisco Bay area .