The enduring and evolving relationship between social class and breast cancer burden: A review of the literature

Introduction: Breast cancer in women has historically been seen as a "cancer of affluence" and there is a well-documented higher incidence among women of higher social class, as well as in societies with higher resources. However, the relationship between social class and breast cancer disease characteristics, especially those associated with poorer prognosis, is less well documented, and the overall relationship between breast cancer mortality and social class has been shown to vary. Furthermore, rapid changes in women's health and health-related behaviors in societies around the world may have an impact on both incidence and mortality patterns for breast cancer in the future. Methods: A PUBMED search on breast cancer and social class (incorporating the MeSH-nested concept of SES) yielded 403 possible studies published between 1978 and 2009, of which 90 met criteria for review. Our review discusses conceptualization and measurement of women's social class in each study, as well as findings related to breast cancer incidence, tumor biology or mortality, associated with social class. Findings: We found mostly consistent evidence that breast cancer incidence continues to be higher in higher social class groups, with some modification of risk with adjustment for known risk factors, including physical activity and reproductive history. However, biologic characteristics associated with poorer prognosis were negatively associated with social class (i.e., greater occurrence among disadvantaged women), and mortality from breast cancer showed inconsistent relationship to social class. Conclusions: We discuss these studies in relation to the growing burden of breast cancer among low resource groups and countries, and the need for cancer control strategies reflecting the emerging demographics of breast cancer risk.