Influence of education level on breast cancer risk and survival in Sweden between 1990 and 2004.

On account of limited recent data regarding the role of education in breast cancer risk and prognosis, we conducted this study to assess the association between education level and in situ and invasive breast cancer risk and invasive breast cancer survival, using the 2006 update of the Swedish Family-Cancer Database. Cox's proportional hazards models were used to calculate the hazard ratio (HR) and 95% confidence interval (CI) adjusted for age, time-period, parity, age at first birth, county of residence, and family history of breast cancer. Compared to women completing less than 9 years of education, university graduates were more likely to be diagnosed with in situ (HR = 1.44, 95% CI: 1.28-1.63) and invasive (HR = 1.28, 95% CI: 1.20-1.36) breast cancer, and the lack of homogeneity between these two HRs was statistically significant, p = 0.007. Further stratification revealed that the lack of homogeneity was greatest for breast cancers diagnosed before age 50. Compared to women completing less than 9 years of education, university graduates were associated with the highest survival following a breast cancer diagnosis (lowest fatality hazard ratio), HR = 0.68, 95% CI: 0.61-0.75. Further research is warranted to elucidate possible behaviors or characteristics associated with education that could explain the differences in incidence and survival, such as compliance with cancer screening. Copyright 2007 Wiley-Liss, Inc.