Objective: Clinical stage (cStage) in thyroid cancer determines extent of surgical therapy and completeness of resection. Pathologic stage (pStage) is an important determinant of outcome. The rate of discordance between clinical and pathologic stage in thyroid cancer is unknown.
Methods: The National Cancer Data Base was queried to identify 27,473 patients ≥45 years old with cStage I through IV differentiated thyroid cancer undergoing surgery from 2008-2012.
Results: There were 16,286 (59.3%) cStage I patients; 4,825 (17.6%) cStage II; 4,329 (15.8%) cStage III; and 2,013 (7.3%) cStage IV patients. The upstage rate was 15.1%, and the downstage rate was 4.6%. For cStage II, there was a 25.5% upstage rate. The change in cStage was a result of inaccurate T-category in 40.8%, N-category in 36.3%, and both in 22.9%. On multivariate analysis, the patients more likely to be upstaged had papillary histology, tumors 2.1 to 4 cm, total thyroidectomy, nodal surgery, positive margins, or multifocal disease. Upstaged patients received radioiodine more frequently (75.3% vs. 48.1%; P<.001).
Conclusion: Approximately 20% of cStage is discordant to pStage. Certain populations are at risk for inaccurate staging, including cT2 and cN0 patients. Upstaged patients are more likely to receive radioactive iodine therapy.
Abbreviations: CI = confidence interval; cStage = clinical stage; DTC = differentiated thyroid cancer; NCDB = National Cancer Data Base; OR = odds ratio; pStage = pathologic stage; RAI = radioactive iodine.