How does the social environment during life course embody in and influence the development of cancer?

Objectives This review assessed the complex longitudinal processes involved in cancer etiology during life course to understand how the social inequality may be embodied in and influence cancer risk. Methods A narrative literature review was performed with a keyword search conducted using PubMed, Scientific Electronic Library Online and Google. Three aspects of literatures were mainly included: social environmental mechanisms of cancer, life course of cancer development and social inequality of cancer risk. This review was complemented with manual searches of relevant journals and reference lists of primary articles. Results Social inequality is mostly embodied in genetic susceptibility and early childhood development, the duration and intensity of exposures and the access to medical resources, which influence the timing and accumulation of cancer risk during life course. Conclusions The individuals with lower socioeconomic status are more likely to have higher cancer risk because of more frequency of timing and quantity of accumulation of adverse exposures and greater impact on epigenetic mechanisms. Primary prevention is the best prevention strategy to reduce cancer risk.