Stage II Differentiated Thyroid Cancer Is a High-Risk Disease in Patients <45/55 Years Old

Abstract

Abstract Purpose The mortality risk of stage II differentiated thyroid cancer (DTC) based on the American Joint Committee on Cancer (AJCC) staging system requires further investigation. Methods Retrospective study of DTC in the US Surveillance, Epidemiology, and End Results program for disease-specific mortality risk in various AJCC stages, with patient age stratification of stage II disease. Results Using AJCC staging system 6.0, hazard ratios (HRs) of mortality for stage II DTC in patients &lt;45 yo and patients ≥45 yo and stages III, IVA, IVB, and IVC compared with stage I were 46.95, 4.95, 9.82, 57.37, 222.10, and 468.68, respectively, showing a robustly higher mortality risk in stage II disease in patients &lt;45 yo than in older patients (P &lt; 0.001), comparable with stage IVA (P = 0.482). Similar results were obtained with AJCC 7.0. With AJCC 8.0, HRs of mortality for stage II in patients &lt;55 yo and patients ≥55 yo and stages III, IVA, and IVB compared with stage I were 75.16, 11.23, 69.45, 134.94, and 235.70, respectively, showing a robustly higher risk in stage II disease in patients &lt;55 yo than in older patients (P &lt; 0.001), comparable with stage III (P = 0.57). Kaplan-Meier survival curves displayed a sharp decline with stage II disease in patients &lt;45/55 yo compared with older patients. Conclusions The mortality risk of stage II DTC was sharply differentiated at patient age 45/55 years, being robustly high in younger patients and comparable with stage III/IVA. This emphasizes the importance of considering age when managing stage II DTC and not treating it as a uniformly low-risk disease.