Metastatic site discriminates survival benefit of primary tumor surgery for differentiated thyroid cancer with distant metastases: A real-world observational study

The role of primary tumor surgery in the management of differentiated thyroid cancer (DTC) with distant metastases (DM) remains controversial. We aimed to explore the survival benefit of primary tumor surgery in patients with different metastatic sites. A retrospective cohort study based on the SEER database was conducted to identify DTC patients with DM diagnosed between 2010 and 2016. Patients were divided into following 2 groups: surgery and non-surgery group. Propensity score weighting was employed to balance clinicopathologic factors between the 2 groups. Of 3537 DTC patients with DM, 956 (66.0%) patients underwent primary tumor surgery while 493 (34.0%) patients did not. There were 798 all-cause deaths and 704 DTC-specific deaths over a median follow-up of 22 months. The weighted 3-year overall survival (OS) for the surgery group was 55.2%, compared to 27.8% (P < .001) for the non-surgery group. The magnitude of the survival difference of surgery was significantly correlated with metastatic sites (P(interaction) <.001). Significant survival improvements in surgery group compared with non-surgery group were observed in patients with lung-only metastasis (adjusted HR = 0.45, P < .001), bone-only metastasis (adjusted HR = 0.40, P < .001), and liver-only metastasis (adjusted HR = 0.27, P < .001), whereas no survival improvement of surgery was found for patients with brain-only metastasis (adjusted HR = 0.57, P = .059) or multiply organ distant metastases (adjusted HR = 0.81, P = .099). The survival benefit from primary tumor surgery for DTC patients with DM varies by metastatic sites. Decisions for primary tumor surgery of DTC patients with DM should be tailored according to metastatic sites.