The impact of microscopic extrathyroid extension on outcome in patients with clinical T1 and T2 well-differentiated thyroid cancer.

To report the impact of microscopic extrathyroid extension (ETE) on outcome in patients with cT1/cT2 well-differentiated thyroid cancer (WDTC), and to determine the effect of extent of surgery and adjuvant radioactive iodine (RAI) treatment on outcome in patients with microscopic ETE. From an institutional database, we identified 984 patients (54%) who underwent surgery for cT1/T2N0 disease. Of these, 869 patients were pT1/T2 and 115 were upstaged to pT3 based on the finding of microscopic ETE. Disease-specific survival (DSS) and recurrence-free survival (RFS) were analyzed for each group using the Kaplan-Meier method. In the pT3 group, factors predictive of outcome were analyzed by univariate and multivariate analyses. There was no difference in the 10-year DSS (99% vs 100%; P = .733) or RFS (98% vs 95%; P = .188) on comparison of the pT1/pT2 and pT3 cohorts. Extent of surgery and administration of postoperative RAI were not significant for recurrence on univariate or multivariate analysis in the pT3 cohort. Outcomes in patients with cT1T2N0 WDTC are excellent and not affected by microscopic ETE. The extent of resection and administration of postoperative RAI in patients with microscopic ETE does not impact survival or recurrence. Copyright © 2011 Mosby, Inc. All rights reserved.