Ethnic density and cancer: A review of the evidence.

Accumulating data suggest that factors in the social environment may be associated with cancer-related outcomes. Ethnic density, defined as the proportion of racial/ethnic minority individuals residing in a given geographic area, is 1 of the most frequently studied social environment factors, but studies on ethnic density and cancer have yielded inconsistent findings. Thus, the objective of the current review was to summarize the extant data on ethnic density and cancer-related outcomes (cancer risk, stage at diagnosis, and mortality) with the aim of identifying pathways by which ethnic density may contribute to outcomes across populations. In general, the findings indicated an association between ethnic density and increased risk for cancers of infectious origin (eg, liver, cervical) but lower risk for breast and colorectal cancers, particularly among Hispanic and Asian Americans. Hispanic ethnic density was associated with greater odds of late-stage cancer diagnosis, whereas black ethnic density was associated with greater mortality. In addition, this review highlights several methodological and conceptual issues surrounding the measurement of ethnic neighborhoods and their available resources. Clarifying the role of neighborhood ethnic density is critical to developing a greater understanding of the health risks and benefits accompanying these environments and how they may affect racial and ethnic disparities in cancer-related outcomes. Cancer 2018;124:1877-903.