Abstract
BACKGROUND: It has been discovered that the prognosis of patients with differentiated thyroid cancer (DTC) correlates with age at initial diagnosis. However, there are disagreements over the optimal cutoff age among the numerous staging and risk stratification criteria, which make it inconsistent to predict the clinical prognosis of specific DTC patients. This study aimed to determine the optimum cutoff age for diagnosis in relation to the clinical outcomes of DTC using data from the Surveillance, Epidemiology and End Results (SEER) database. METHODS: The best age cutoff value was determined by the X-tile software. The link between clinical characteristics and cancer-specific survival (CSS) was examined using univariate and multivariate Cox regression models. An additional application of the independent prognostic criteria, such as age stratifications, was applied to construct a nomogram model for predicting the chances of patient survival. RESULTS: The most accurate diagnosis cutoff age for DTC patients was suggested to be 67 years old. The multivariate analysis, using factors determined by univariate analysis, showed that age [>67 years, hazard rate (HR) =5.049, 95% confidence interval (CI): 4.509-5.653, P<0.001], sex (female, HR =0.651, 95% CI: 0.584-0.727, P<0.001), tumor size (>20 and ≤40 mm, HR =2.296, 95% CI: 1.983-2.658, P<0.001; >40 mm, HR =4.976, 95% CI: 4.304-5.752, P<0.001), lymphadenectomy (HR =1.337, 95% CI: 1.186-1.506, P<0.001), distant metastasis (HR =12.166, 95% CI: 10.749-13.769, P<0.001) and surgical treatment (HR =0.173, 95% CI: 0.144-0.210, P<0.001) were independent factors for CSS. Patients in the high-risk group had worse survival rates, and the C-index for the CSS prediction model with age (cutoff of 67) and other independent clinicopathological variables was 0.906. CONCLUSIONS: Accordingly, the optimal cutoff age for predicting death from DTC specifically is 67 years old at the time of the initial diagnosis. It might be a more suitable factor when used in risk stratification for patients with DTC.