Incidence of brain and Central Nervous System cancer in Foggia’s area

Background: Disease mapping techniques are widely used in small-area studies to account for spatial patterns in the disease rates. We screened the trends in the geographical patterns of brain and Central Nervous System (CNS) cancer incidence in the province of Foggia over a period of 5 years (2005-2009). Methods: Case data were collected in 60 municipalities. Standardized incidence ratios (SIR) were calculated for each town under an internal standardization. For map plotting purposes, smoothed relative risks were calculated using the conditional autoregressive model proposed by Besag, York and Mollie. It fits a Poisson spatial model adjusting for the presence of spatial correlation and extra-Poisson variation in area-specific relative risks. The adjustment for an area-specific urbanization index was also considered. Results were estimated for women, men and both sexes. Results : The annual crude incidence rate for brain and CNS tumors in the Foggia province was 11.40 (95% CI 9.7-13.1) per 100,000 men and 12.42 (95% CI 10.7-14.1) per 100,000 women. Adjusted smoothed SIRs varied from 0.43 (95% CI 0.10-0.87) to 2.22 (95% CI 0.89-5.81), showing higher risks in the central of the province, in particular in Foggia. Conclusion: Bayesian spatial models are increasingly used by public health because they produce smooth risk surfaces which identify well-defined geographical clusters. This study reveals significant geographic differences in brain and CNS tumors incidence, with higher incidence in the main urban areas. Urbanization is a possible surrogate of real determinants of this phenomenon. Further investigations are needed to explore this hypothesis.