Thyroid Cancer Incidences From Selected South America Population-Based Cancer Registries: An Age-Period-Cohort Study

PurposeThe incidence of thyroid cancer (TC) has increased substantially worldwide. However, there is a lack of knowledge about age-period-cohort (APC) effects on incidence rates in South American countries. This study describes the TC incidence trends and analyzes APC effects in Cali, Colombia; Costa Rica; Goiânia, Brazil; and Quito, Ecuador.Materials and MethodsData were obtained from the Cancer Incidence in Five Continents series, and the crude and age-standardized incidence rates were calculated. Trends were assessed using the estimated annual percentage change, and APC models were estimated using Poisson regression for individuals between age 20 and 79 years.ResultsAn increasing trend in age-standardized incidence rates was observed among women from Goiânia (9.2%), Costa Rica (5.7%), Quito (4.0%), and Cali (3.4%), and in men from Goiânia (10.0%) and Costa Rica (3.4%). The APC modeling showed that there was a period effect in all regions and for both sexes. Increasing rate ratios were observed among wo...