Histologic subtypes of papillary thyroid cancer affect prognosis. The objective of this study was to examine whether survival is affected by extent of surgery for conventional versus follicular-variant papillary thyroid cancer when stratified by tumor size.

Using the National Cancer Data Base, we evaluated 33,816 adults undergoing surgery for papillary thyroid cancer from 2004 to 2008 for 1.0-3.9 cm tumors and clinically negative lymph nodes. Conventional and follicular-variant papillary thyroid cancers were divided into separate groups. Cox regression models stratified by tumor size were used to determine if extent of surgery affected overall survival.

A total of 30,981 patients had total thyroidectomy and 2,835 had thyroid lobectomy; 22,899 patients had conventional papillary thyroid cancer and 10,918 had follicular-variant papillary thyroid cancer. On unadjusted KM analysis, total thyroidectomy was associated with improved survival for conventional (P = 0.02) but not for follicular-variant papillary thyroid cancer patients (P = 0.42). For conventional papillary thyroid cancer, adjusted analysis showed total thyroidectomy was associated with improved survival for 2.0-3.9 cm tumors (P = 0.03) but not for 1.0-1.9 cm tumors (P = 0.16). For follicular-variant, lobectomy and total thyroidectomy had equivalent survival for 1.0-1.9 cm (P = 0.45) and 2.0-3.9 cm (P = 0.88) tumors.

Tumor size, histologic subtype, and surgical therapy are important factors in papillary thyroid cancer survival. Total thyroidectomy was associated with improved survival in patients with 2.0-3.9 cm conventional papillary thyroid cancer, and should be considered for 2.0-3.9 cm papillary thyroid cancers when preoperative molecular analysis is not used to distinguish conventional from follicular-variant.