TIMING OF RADIOACTIVE IODINE THERAPY DOES NOT IMPACT OVERALL SURVIVAL IN HIGH-RISK PAPILLARY THYROID CARCINOMA.

OBJECTIVE: Postthyroidectomy radioiodine (RAI) therapy is indicated for papillary thyroid carcinoma (PTC) with high-risk features. There is variability in the timing of RAI therapy with no consensus. We analyzed the impact of the timing of initial RAI therapy on overall survival (OS) in PTC.

METHODS: The National Cancer Data Base (NCDB) was queried from 2003 to 2006 for patients with PTC undergoing near/subtotal or total thyroidectomy and RAI therapy. High-risk patients had tumors >4 cm in size, lymph node involvement, or grossly positive margins. Early RAI was ≤3 months, whereas delayed was between 3 and 12 months after thyroidectomy. Kaplan-Meier (KM) and Cox survival analyses were performed after adjusting for patient and tumor-related variables. A propensity-matched set of high-risk patients after eliminating bias in RAI timing was also analyzed.

RESULTS: There were 9,706 patients in the high-risk group. The median survival was 74.7 months. KM analysis showed a survival benefit for early RAI in high-risk patients (P = .025). However, this difference disappeared (hazard ratio [HR] 1.26, 95% confidence interval [CI] 0.98-1.62, P = .07) on adjusted Cox multivariable analysis. Timing of RAI therapy failed to affect OS in propensity-matched high-risk patients (HR 1.09, 95% CI 0.75-1.58, P = .662).

CONCLUSION: The timing of postthyroidectomy initial RAI therapy does not affect OS in patients with high-risk PTC.

ABBREVIATIONS: CI = confidence interval CLNM = cervical lymph node metastasis FVPTC = follicular variant papillary thyroid carcinoma HR = hazard ratio KM = Kaplan-Meier NCDB = National Cancer Data Base OS = overall survival PTC = papillary thyroid carcinoma RAI = radioactive iodine.