SOCIOECONOMIC-STATUS AND BREAST-CANCER INCIDENCE - A PROSPECTIVE COHORT STUDY

Background. To gain more insight into the relation between socioeconomic status (SES) and breast cancer risk, we have studied that association, before and after adjustment for traditional risk factors for breast cancer, in a prospective cohort study on lifestyle and cancer that started in 1986 in the Netherlands amongst 62573 women aged 55-69 years. Methods. At baseline, data on SES, diet, reproductive factors and other covariates were collected by means of a self-administered questionnaire. For data-analysis a case-cohort approach was used. After 3.3 years of follow-up, 471 incident cases were available for analysis. Results. We did not find a higher age-adjusted risk of breast cancer for those with a higher level of education (RR highest/lowest level of education = 0.94, 95% confidence interval [CI] : 0.63-1.39, trend-P = 0.15). Although upper white-collar workers had a slightly higher breast cancer risk than blue-collar workers (RR = 1.16, 95% CI : 0.83-1.62, trend-P = 0.34), women with a profession of higher social standing did not have a higher risk (RR highest/lowest social standing = 0.73, 95% CI : 0.24-2.23, trend-P = 0.86). Additional adjustment for traditional risk factors did not alter the association between SES and breast cancer risk. Conclusions. We did not find an association between SES and breast cancer risk. This is not in agreement with studies conducted in other European countries and North America.