Background: The epidemiology of thyroid cancer has changed radically in the recent past, with rising international incidence of early-stage papillary thyroid cancer (PTC) in particular. In this paper, we review the epidemiology of thyroid cancer in Ireland.
Methods: A retrospective cohort study of National Cancer Registry of Ireland data, 1994-2019.
Results: Records from 4,158 patients were analyzed. 73% (n=3,040) were female. The average age was 50 years. Gender did not change over time (p=0.662), while age decreased significantly (p<0.0001). The most common diagnoses were PTC (n=2,905, 70%) and follicular thyroid carcinoma (n=549, 13%). Incidence rose over threefold (1.8 to 6.2 cases/100,000 person-years). The incidence of T1 PTC rose over twelvefold (0.2 to 2.1 cases/100,000 person-years), while the incidence of stage III and IV disease did not change significantly. 38% (n=1,571) of cases were treated in the Dublin/Mid-Leinster region, compared with 23% (n=950) in the South of Ireland ““ the proportion treated in Dublin/Mid-Leinster rose significantly (p<0.001). Five-year disease-specific survival was 85% and varied significantly by diagnosis ““ 97% for PTC versus 5% for anaplastic thyroid carcinoma.
Conclusion: The epidemiology of thyroid cancer in Ireland has changed dramatically reflective of international trends.