Ethnic Enclaves and Incidence of Cancer Among US Ethnic Minorities in the Multi-Ethnic Study of Atherosclerosis.

Background: Since immigrants and their descendants represent a growing proportion of the US population, there is a strong demographic imperative for scientists to better understand the cancer risk factors at multiple levels that exist for these populations. Understanding the upstream causes of cancer, including neighborhood context, may help prevention efforts. Residence in ethnic enclaves may be one such contextual cause; however, the evidence is mixed, and past research has not utilized prospective designs examining cancer incidence or mortality.

Methods: We examined the association between residency in ethnic enclaves and cancer events among Hispanic (n = 753) and Chinese (n = 451) participants without a history of cancer in the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective cohort study that enrolled participants ages 45-84 in six US cities. Cancer events included deaths and hospitalization for any cancer diagnosis from 2000-2012. Residency in an ethnic enclave was operationalized as their geocoded baseline census tract having a concentration of residents of the same ethnicity greater than the 75th percentile (compared to non-ethnic enclave otherwise). Potential confounders were blocked into three categories: sociodemographic, acculturation, and biomedical/health behavior variables. To examine the association between ethnic enclaves and cancer, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) using Cox proportional hazards models.

Results: Among Hispanic participants, residing in ethnic enclaves (vs. not) was associated with a 39% reduction in cancer risk (HR 0.61, 95%CI: 0.31, 1.21) after adjusting for sociodemographic variables. Among Chinese participants, residing in ethnic enclaves was associated with a 2.8-fold increase in cancer risk (HR 2.86, 95%CI; 1.38, 5.94) after adjusting for sociodemographic variables.

Conclusions: Our results suggest that the association between ethnic enclaves and cancer events differs by ethnic group, suggesting that different social and contextual factors may operate in different communities.