Impact of distant metastasis on overall survival and cancer specific survival of elderly patients with differentiated thyroid cancer

Distant metastases are common in most elderly patients, because elderly patients are diagnosed with advanced thyroid cancer due to delayed diagnosis. There is still few specific real-world data regarding prognosis in the elderly with differentiated thyroid cancer (DTC). The purpose of this study is to evaluate the prognostic factors and survival rate of elderly DTC patients with metastasis. This retrospective study included 14,603 elderly patients diagnosed with DTC from 2010 to 2015, including 447 patients with distant metastasis via the Surveillance, Epidemiology and End Results (SEER) database. The prognostic factors of overall survival (OS) and cancer-specific survival (CSS) in elderly DTC patients with metastasis or non-metastasis were determined by univariate and multivariate analysis. Age, primary site operation, radiotherapy, chemotherapy and tumor size are associated with OS and CSS in elderly DTC patients with distant metastasis. Compared with the patients without surgery, patients with total thyroidectomy showed significantly better OS. For the elderly DTC patients, radiotherapy was associated with improving OS and CSS. Chemotherapy increased the risk of death. For elderly DTC patients, early identification of distant metastasis, total thyroidectomy and radiotherapy are associated with better prognosis.