Is radioiodine ablation with 30 mCi 131I necessary in low-risk thyroid cancer patients? Results from a long-term follow-up prospective study.

Abstract

Abstract In patients with low-risk differentiated thyroid cancer (DTC), remnant ablation with radioiodine (RA) after total thyroidectomy (TT) is controversial. No benefits have been demonstrated in terms of mortality or disease-free survival. Recent evidence found that RA did not improve mid-term outcomes. Purpose: to evaluate initial response to treatment and long-term follow-up status in low-risk DTC patients after TT vs. TT+RA. Methods: prospective multicenter non-randomized study; 174 low-risk DTC that underwent TT were recruited and were divided in two groups according to RA (87 ablated and 87 non-ablated). Response to treatment was evaluated between 6-18 months after thyroidectomy and at the end of follow-up with thyroglobulin, anti-thyroglobulin antibodies levels and neck ultrasonography. Results: baseline characteristics of both groups were similar. Ablated patients: median age 45.5 years, 84% females, 95.4% papillary thyroid carcinoma (PTC), mean tumor size 16mm; non-ablated: median age 45 years, 88.5% females, 96.6% PTC, mean tumor size 14 mm. Response to initial treatment was similar between both groups, with less than 2% of structural incomplete response. Final status was evaluated in 139 cases after a median follow-up of 60 months. Among ablated patients, 82.8% had no evidence of disease (NED), 12% had an indeterminate response (IR) and 5% a biochemical incomplete response (BIR). Non-ablated patients had NED in 90%, IR in 8.7% and BIR in 1.2%. No statistical difference was found between groups (p=0.29). No patient had evidence of structural disease at the end of follow-up. Conclusions:our findings support the recommendation against routine RA in low-risk DTC patients.