Do cancer registries play a role in determining the incidence of non-melanoma skin cancers?

Non-melanoma skin cancers have the highest incidence of all malignancies worldwide. However, cancer registries rarely include data on non-melanoma skin cancers because they tend to be under-reported. To determine incidence rates and changes over time for non-melanoma skin cancers in a mid-sized Brazilian population. We calculated age-standardized rates, adjusted to the world population using the direct method, from 1996-2012 in the Aracaju Cancer Registry and then calculated incidence trends using the Joinpoint Regression Program. We analysed 11,476 cases (5,695 men and 5,781 women) of non-melanoma skin cancer collected during the study period. The histological subtypes in men were 84.5% basal cell carcinoma, 14.5% squamous cell carcinoma, and 1% other histological subtypes, whereas the corresponding percentages in women were 89.1%, 10%, and 0.9%, respectively. Average incidence age-standardized rates were 228.6 (95% CI: 221.6; 235.6) per 100,000 men and 145.4 (95% CI: 141.0; 149.9) per 100,000 women. The incidence mostly increased in the first years for the series and then stabilized. The under-reporting of non-melanoma skin cancers, due to removal of lesions without histopathological confirmation, decisions to keep skin lesions under observation instead of excising them, and deferring medical examination, is a potential pitfall of this study. Age-standardized incidence of non-melanoma skin cancer was high during the study period, but tended to stabilise in the latter years of the study.