Association between primary tumor resection and survival in metastatic follicular thyroid carcinoma: a real-world population‑based cohort Study

Abstract The clinical value of primary tumor resection (PTR) for patients with de novo metastatic follicular thyroid carcinoma (FTC) remains controversial due to insufficient subtype-specific real-world evidence. This study aimed to comprehensively evaluate the association between PTR and survival in patients with metastatic FTC using a population-based cohort. Patients with newly diagnosed FTC between 2010 and 2020 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan–Meier survival curves and log-rank tests were used to compare overall survival (OS) and cancer-specific survival (CSS) between patients treated with and without PTR. Propensity score matching (PSM) was conducted to balance baseline clinicopathological confounders. Multivariable Cox regression analyses were performed to identify independent prognostic factors. Among 7636 FTC patients, 363 (4.75%) presented with synchronous distant metastasis at initial diagnosis. Of these metastatic cases, 238 (65.5%) received PTR, while 125 did not. Patients who underwent PTR were younger than those who did not (mean age 65.18 ± 13.08 vs. 70.30 ± 12.61 years, P < 0.01). In the entire cohort, patients undergoing PTR exhibited significantly longer median OS (70.0 vs. 27.0 months, P < 0.01) and median CSS (98.0 vs. 47.0 months, P < 0.01) than non-surgical patients. A survival advantage associated with PTR was also observed in several subgroups; the direction of the association was similar after PSM, although the matched cohort was small. The multivariable Cox regression analysis after adjustment for age and other confounders showed PTR was independently associated with a reduced risk of all‑cause mortality (HR=0.52, 95%CI 0.35–0.79, P < 0.01) and cancer-specific mortality (HR=0.49, 95%CI 0.31–0.79, P < 0.01). PTR is significantly associated with improved OS and CSS for patients with de novo metastatic FTC in this real-world cohort.