Comparison of prognosis between oncocytic thyroid carcinoma and follicular thyroid carcinoma: a population-based propensity score matching analysis.

Background: Oncocytic thyroid carcinoma (OTC) is a rare subtype of thyroid cancer known for its distinctive morphology and high likelihood of recurrence, setting it apart from follicular thyroid carcinoma (FTC). Despite this, there is limited research comparing the clinicopathological characteristics and outcomes of OTC and FTC.

Methods: We retrospectively searched through the Surveillance, Epidemiology, and End-Results (SEER) database (2004-2015) for histologically diagnosed OTC and FTC patients. Kaplan-Meier analysis, propensity score matching (PSM), univariate Cox proportional risk regression model, and subgroup analysis were employed to investigate the prognostic effect of clinicopathological features and treatment regimens on survival outcomes of OTC and FTC patients.

Results: 2329 OTC patients and 5679 FTC patients were included in the study. OTC patients were prone to older age, white race, lymph node metastasis, distal metastasis, extension and multiple primary tumors compared with FTC patients. After using a 1:1 PSM matching ratio, there were no significant differences in demographic and clinicopathological characteristics between the matched groups. Further Cox regression analysis showed that OTC patients had lower overall survival (OS) and cancer-specific survival (CSS) in contrast with FTC patients. Subgroup survival analysis suggested that the OTC patients were related to lower OS in subgroups including those over 55 years old, male sex, white ethnicity, extrathyroidal extension, single primary tumor, surgery and without chemotherapy compared with the FTC patients in these subgroups. In addition, the OTC patients were connected with lower CSS in subgroups including male sex, white ethnicity, married status, tumor size is less than 20 mm or more than 40 mm, N0 stage, localized stage, single primary tumor, surgery, radiotherapy, and without chemotherapy compared with the FTC patients in these subgroups. Meanwhile, the OTC patients had lower CSS compared to FTC patients regardless of age and extrathyroidal extension.

Conclusions: The results suggested that OTC patients have unique clinical features and poorer prognoses compared to FTC patients. Surgical resection and radioactive iodine therapy are recommended for OTC patients and FTC patients. It is worth noting that the prognosis of OTC relies largely on the selection of treatment strategies. Therefore, our results highlighted the clinical significance of the early distinguishment and the correct choice of treatment in OTC patients.