Background: 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.
Methods: 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.
Results: 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.
Conclusion: 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.
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