Impact of Extent of Surgery on Long-Term Prognosis of Follicular Thyroid Carcinoma Without Extrathyroidal Extension and Distant Metastasis

Aim To analyze the effect of total thyroidectomy (TT) and thyroid lobectomy (LT) on the long-term prognosis of follicular thyroid carcinoma (FTC) without extrathyroidal extension and distant metastasis and to clarify whether the tumor size (<= 40 mm vs. > 40 mm) has an important impact on the extent of surgery. Methods Data on FTC patients without extrathyroidal extension and distant metastasis treated with either TT or LT between 1998 and 2016 were extracted from the Surveillance, Epidemiology, and End Results Database. Propensity score matching was performed to minimize impact of selection bias and potential confounding. Kaplan-Meier curves and Cox regression analysis were conducted to assess the impact of the extent of surgery on disease-specific survival (DSS). Results A total of 8435 patients were identified. The DSS after LT were 100%, 98.3%, and 97.6% at 5, 10, and 15 years, respectively, compared with those seen after TT of 99.3%, 97.9%, and 96.6%. The difference between the two groups is not statistically significant (p = 0.083). Similar results were observed in cohorts after adjusting for baseline covariates. There was also similar prognosis between LT and TT in patients with tumors size <= 40 mm or > 40 mm. Conclusions For patients with FTC of any size without extrathyroidal extension and distant metastases at diagnosis, TT and LT confer equivalent DSS. Completion thyroidectomy after LT may be not necessary unless patients relapse; however, recurrence rates and development of metastases are not evaluated in this study.