Incidence and mortality risk for respiratory tract cancer in the city of São Paulo, Brazil: Bayesian analysis of the association with traffic density.

BACKGROUND: There is evidence that exposure to traffic-related air pollution is related to the incidence of and mortality associated with lung cancer. The aim of this study was to perform a spatial analysis, with a Bayesian approach, to test the hypothesis that high traffic density is associated with increased respiratory tract cancer incidence and mortality risk among individuals over 20 years of age residing in the city of São Paulo, Brazil.

METHODS: We employed data from two different databases: the São Paulo Municipal Population-Based Cancer Registry (2002-2011 cancer incidence data); and the Mortality Database of the São Paulo Municipal Health Department (2002-2013 cancer mortality data). The relationships between the number of cases of respiratory tract cancer in each area analyzed and the standardized covariates-traffic density and the Municipal Human Development Index (MHDI)-were evaluated with a Besag-York-Mollié ecological model with relative risks (RRs) estimates.

RESULTS: Per 1-unit standard-deviation increase in traffic density and in the MHDI, the RR for respiratory tract cancer incidence was 1.07 (95% CI: 1.02-1.13) and 1.25 (95% CI: 1.18-1.32), respectively, whereas the RR for mortality was 1.04 (95% CI: 0.99-1.09) and 1.23 (95% CI: 1.16-1.30), respectively.

CONCLUSION: Our findings support the hypothesis that residing in areas with high traffic density is associated with increased respiratory tract cancer incidence and mortality risk in the city of São Paulo.