The Role of Early-Life Socioeconomic Status in Breast Cancer Incidence and Mortality: Unraveling Life Course Mechanisms

Objectives: We examine (a) how breast cancer onset and survival are affected by various dimensions of early-life socioeconomic status (SES) and (b) the extent to which women's characteristics in adulthood mediate the associations between early-life conditions and breast cancer. Method: We apply Cox regression models and a decomposition analysis to the data from the 4,275 women in the Wisconsin Longitudinal Study. Results: Higher levels of mothers' education and early-life family income were associated with a greater risk of breast cancer incidence. The effect of mothers' education was mediated by women's adult SES and reproductive behaviors. Fathers' education was related negatively to breast cancer mortality, yet this effect was fully mediated by women's own education. Discussion: This study identifies mechanisms linking early-life social environment to breast cancer onset and mortality. The findings emphasize the role of social factors in breast cancer incidence and survival.