Thyroid Lobectomy for T1b-T2 Papillary Thyroid Cancer with High-Risk Features.

BACKGROUND: Thyroid lobectomy (TL) has been proposed as definitive surgical treatment for papillary thyroid cancers (PTC) up to 4 cm. This study evaluates the use and appropriateness of TL for T1b and T2 PTC.

STUDY DESIGN: The National Cancer Database was interrogated for adult patients having TL for T1b-T2 PTC between 2004 and 2014. Patients who should have undergone total thyroidectomy (TT) instead of lobectomy based on high-risk tumor features were identified. The 2 groups were compared for clinical and demographic characteristics, and overall survival.

RESULTS: Of 8,083 patients undergoing lobectomy, 1,552 patients had high-risk features and should have undergone TT. These included 194 with cN1, 571 with pN1, 307 with lymphovascular invasion (LVI), 645 with extra thyroidal extension (ETE), 567 with positive margins, 42 with poorly differentiated PTC, and 25 with M1 disease. At 10 years of follow-up, 92.4% of appropriate lobectomy (aTL) patients were alive compared with 88.5% of inappropriate lobectomy (iTL) patients (p < 0.001). On univariate and multivariable Cox survival analysis, age greater than 45 years, male sex, comorbidities, government or no insurance, low income, and tumor size >2 cm were associated with poorer survival (all p < 0.05). Thyroid lobectomy patients with high-risk features had significantly higher mortality on unadjusted (hazard ratio [HR] 1.98, 95% CI 1.52 to 2.59, p < 0.001) and adjusted survival analysis (HR 1.97, 95% CI 1.51 to 2.58, p < 0.001). Total thyroidectomy with radioiodine treatment had improved overall survival in comparison to iTL (HR 0.65, 95% CI 0.51 to 0.83, p < 0.001).

CONCLUSIONS: A substantial number of patients (19.2%) with tumor size >1 cm and high-risk features undergo thyroid lobectomy for PTC. Exclusion of high-risk features is important when adopting lobectomy as the definitive surgical therapy for T1b and T2 PTC because they have a potential adverse effect on long-term survival.