Is Lobectomy Sufficient for Multifocal Papillary Thyroid Microcarcinoma?

Importance: Multifocal papillary thyroid microcarcinoma (PTMC) has been associated with a higher incidence of lymph node involvement, bilateral involvement, and extrathyroidal extension compared to unifocal papillary thyroid cancer (PTC).Objective: To describe the incidence and determinants of survival for patients with multifocal PTMC using the Surveillance, Epidemiology, and End Result (SEER) database.Design, setting, participants: The SEER registry was utilized to calculate survival trends for patients with PTMC between 2010 and 2015. Patient data was then analyzed with respect to age, sex, race, multifocality, and types of surgery rendered.Main outcomes and measures: Overall Survival (OS) and Disease Specific Survival (DSS).Results: 22,283 cases of papillary thyroid microcarcinoma (T1a N0 M0) were identified. The cohort was composed of 82.6 % females, and about 82 % of patients were of white race. The mean age at diagnosis was 51.9 years. Multifocal PTMC was present in 32.2 % of the tumors (n = 7186). 73.9 % of patients underwent total thyroidectomy and 23.0 % received lobectomy. OS at 2 and 5 years was 98 % and 95 %, respectively. Multivariate analysis revealed that age, sex, and multifocality were determinants of OS. Only age was a determinant of DSS. Kaplan-Meier survival analysis revealed that multifocal PTMC had similar mean OS between lobectomy and total thyroidectomy patients (69.59 months versus 69.82 months). Conclusions and relevance: PTMC has a good prognosis. Our analysis revealed that age was a determinant of OS and DSS; sex and multifocality were also prognosticators for OS. The type of surgery, whether lobectomy or total thyroidectomy, was not a determinant of survival in multifocal PTMC.