Socioeconomic factors and cancer incidence, mortality, and survival in a metropolitan area of Japan: a cross-sectional ecological study.

Cancer mortality is generally high in people of low socioeconomic status compared with people of high socioeconomic status (SES). Although these differences in mortality may be caused by differences in cancer incidence and survival, analysis of these factors has rarely been conducted. The objective of our cross-sectional ecological study was to analyze socioeconomic differences in cancer incidence, mortality and survival in a metropolitan area of Japan. The age-adjusted cancer incidence rates, age-adjusted mortality rates, relative 5-year survival, and proportions of early stage cancer were calculated for 67 municipalities in Osaka, Japan. For area-based socioeconomic variables, we used the percentages of male unemployment, college or graduate school graduates, home ownership, households receiving government assistance, and households below the subsistence habitation level in each municipality. We performed linear regression taking each municipality's population as weight to examine the relationships between measurements relating cancer and socioeconomic variables. Factor analysis of socioeconomic variables was carried out to determine whether a particular socioeconomic variable tended to be associated with another. Cancer incidence, cancer mortality, 5-year cancer survival, and proportion of early stage cancer were highly correlated with each socioeconomic variable at the municipality level. Five area-based socioeconomic variables could be explained by three factors: economic status, housing characteristics and educational attainment. Despite the major limitation of a lack of individual information about socioeconomic characteristics and outcomes related to cancer, we hypothesize that a municipal area's socioeconomic status might be a predictor of individual incidence, mortality, and survival of cancer.