Thyroid Cancer Incidence in North-East Spain, 2002–2021: A Population-Based Study

Abstract

Simple Summary Thyroid cancer has become one of the most rapidly growing cancer diagnoses worldwide over recent decades, largely attributed to the increased detection of small, clinically insignificant tumors through improved imaging technologies—a phenomenon known as overdiagnosis. However, this rise cannot be explained by detection alone. This study examines how the incidence of thyroid cancer has changed over a 20-year period (2002–2021) in the province of Girona, Spain, using data from a population-based cancer registry. The findings confirmed a steady increase in incidence, predominantly affecting women and driven by early-stage papillary tumors, which may be consistent with overdiagnosis. Notably, a concerning rise in intermediate-stage cases and a narrowing gap between sexes in older age groups suggest that additional risk factors beyond improved detection may be at play. These results highlight the need for more tailored clinical approaches and continued epidemiological surveillance in this population.