Prognosis of patients with TX stage differentiated thyroid cancer: propensity scored matching analysis of the SEER database 2004-2013.

In differentiated thyroid cancer (DTC), TX stage is defined as 'primary tumour cannot be assessed'. The prognosis of patients with TX stage remains unclear. The aim of this study was to investigate the prognosis of TX stage and provide a perspective on treatment guidelines. We investigated a large cohort of DTC patients from the Surveillance, Epidemiology, and End Results database between 2004 and 2013. Patient mortality was examined by Kaplan-Meier analyses with log-rank tests and Cox proportional hazards regression analyses. The rate of cancer-specific mortality per 1000 person-years for patients with TX stage was higher than for patients with T1-T3 stage, but lower than for patients with T4 stage. The all-cause mortality per 1000 person-years for TX stage patients was also higher than for T1-T3 stage patients, but lower than for T4 stage patients. TX stage showed significant risk for cancer-specific mortality compared to T1 and T4 stages, but not T2 and T3 stages, after adjusting for influential risk factors. TX stage patients showed no significant risk for all-cause mortality compared to T2-T3 stage patients, but were different than T1 and T4 stage patients. These results provide new implications for the treatment of TX stage DTC patients.