Colorectal cancer mortality in Mato Grosso, Brazil: Spatiotemporal trends

Mortality due to colorectal cancer is increasing in Brazil, but an organised approach to screening and prevention is lacking. Considering the importance of this disease, the present study examines recent mortality trends of colorectal cancer mortality in the meso- and microregions in the state of Mato Grosso with the objective of analysing spatiotemporal trends to help guide the allocation of health services related to this type of cancer. Mortality data from the Brazilian national public health system from 1996 to 2015 were analysed investigating spatiotemporal trends using Conditional Autoregressive (CAR) models, a class of Bayesian hierarchical models that rely on Markov Chain Monte Carlo (MCMC) simulations. Convergence issues arose with several types of CAR models, but notably not with the linear variant, which models the mortality within each spatial region as a linear function of time. Men and women of all ages displayed higher and increasing mortality rates in the Cuiabá and Rondonópolis microregions. Additional regions of increasing mortality were found for specific age and gender strata. It was concluded that spatiotemporal modelling is a useful tool for the characterisation of diseases, including cancer, which are influenced by several factors and need to be monitored over space and time. The combination of spatial and temporal analyses of mortality shown in this paper unveils important information regarding the small areas dynamics, which may guide discussions, regulation and application of decentralised public health policies.