The prognosis of NX stage differentiated thyroid cancer based on propensity score matching and SEER data

Few studies have evaluated the prognosis or treatment of patients with differentiated thyroid cancer (DTC) according to their NX status. This study investigated this issue to provide a new perspective regarding the treatment guidelines for these patients. Data from 92,447 patients with DTC were obtained from the Surveillance, Epidemiology, and End Results (SEER) database (2004-2013). Survival outcomes were evaluated using Kaplan-Meier analyses with the log-rank test and Cox proportional hazards regression analysis. The rates of cancer-specific mortality and all-cause mortality (per 1,000 person-years) were significantly higher for patients with NX disease, compared to patients with N0 or N1 disease. Multivariate Cox regression modeling revealed that NX stage was an independent risk factor for cancer-specific mortality compared to N1 stage, but not to N0 stage. Similar results were observed for all-cause mortality. After adjustment using propensity score matching, the cancer-specific and all-cause mortality rates were lower for NX stage compared to N0 stage, whereas no significant difference was observed when comparing the NX stage and N1 stage groups. The unexpectedly poor prognosis of patients with NX stage DTC provides new information that may be relevant for treating these patients.