Clinical Significance of Gross Invasion of Strap Muscles in Patients With 1- to 4-cm-Sized Papillary Thyroid Carcinoma Undergoing Lobectomy.

ABSTRACT

BACKGROUND: Given the emerging evidence supporting the lack of prognostic significance of gross extrathyroidal extension invading only strap muscles (strap-gETE), this study investigated whether lobectomy is feasible for patients with strap-gETE. METHODS: A retrospective cohort study was conducted with 636 patients who had 1- to 4-cm-sized papillary thyroid carcinoma (PTC) treated with thyroid lobectomy. Patients with gross invasion of perithyroidal organs other than strap muscles or synchronous distant metastasis were excluded from the study. Disease-free survival (DFS) was compared according to the presence of strap-gETE. RESULTS: Strap-gETE was present in 50 patients (7.9%), with the remaining 586 patients (92.1%) showing no evidence of gETE. During the median follow-up period of 7.4 years, 6% of the patients with strap-gETE and 5.1% of the patients without gETE experienced structural persistent/recurrent disease (p = 0.99). No differences in DFS were observed between the two groups (hazard ratio [HR], 1.24; 95% confidence interval [CI], 0.38-4.08; p = 0.720). After adjustment for five major risk factors (age, gender, tumor size, multifocality, and cervical lymph node metastasis status) in the multivariate analysis, the presence of strap-gETE did not exhibit an independent role in the development of structural persistent/recurrent disease (HR 1.05; 95% CI 0.24-4.53, p = 0.950). CONCLUSIONS: Strap-gETE did not increase the risk of structural persistent/recurrent disease for the patients who underwent lobectomy for 1- to 4-cm-sized PTC. The study data support the limited role of strap-gETE in clinical outcomes and may broaden the indications for lobectomy for patients with PTCs.