Socioeconomic inequalities in cancer incidence and mortality: Review of ecological studies, 1998-2008

Introduction: Socioeconomic inequalities are manifested in the incidence and mortality from malignant neoplasms. Ecological studies represent a key approach in epidemiology and can contribute for research on the social determinants of health events. Objective: To investigate the associations between socioeconomic status and the incidence and mortality from cancer and its types, through review of ecological studies. To define the real importance played by ecological studies in the investigation of this relationship. Method: Main regional and international databases were searched for articles in Portuguese, Spanish and English published between 1998 and 2008. Results: 32 eligible studies were included. There was positive and consistent association of the socio-economic level of the area of residence with: incidence of prostate cancer and with mortality by colon cancers in men; incidence and mortality for breast cancer and incidence of colon cancer in women. Negative and consistent association was found for: incidence and mortality of esophagus and stomach cancers; incidence of lung and colon cancers and mortality of larynx and oral cavity cancers in men; for incidence and mortality of esophagus, stomach and cervix cancers and incidence of colon and lung cancers in women. Conclusion: Despite the presence of residual effects of area and bias related to the aggregated measurement of socioeconomic level, ecological studies can be efficiently used in the measurement of socioeconomic inequalities in cancer. The use of small geographic units and data from cancer registries in developing countries can contribute to a better knowledge of their health inequalities.