Radioiodine remnant ablation in low-risk differentiated thyroid cancer patients who had R0 dissection is an over treatment.

Low-risk (LR) differentiated thyroid cancer (DTC) patients should be ablated or not, albeit, with small dose of radioiodine is highly controversial. We hypothesized that those LR DTC patients who were surgically ablated need no radioiodine remnant ablation (RRA). This study aims to evaluate the long-term outcome in these two groups of patients. Retrospective cohort study conducted from January 1991 to December 2012. Based on extent of surgical resection and histopathology, LR DTC patients were classified as Gr-1: 169 patients, who were surgically ablated; Gr-2: 153 patients, who had significant remnant in thyroid bed. Basal parameters were comparable between two groups except pretherapy 24 h radioiodine uptake (0.16 ± 0.01% vs. 5.64 ± 0.46%; P < 0.001). No patient received RRA in Gr-1; Gr-2 patients were administered 30 mCi (131) I. Total number of events (recurrence, persistent, and progression of disease), with median follow up of 10.3 years, was observed in 10/322 (3.1%) of LR DTC patients. Only one patient had disease recurrence from Gr-1, who became disease-free after radioiodine therapy. Similarly, one patient from 126, who was ablated with single dose of RRA, had recurrence from Gr-2. However, 8/27 (29.7%) patients from Gr-2 had persistent disease; even two of them subsequently developed disease progression, who failed first-dose of RRA. The event-free survival rates were 99.4% and 94.1% (P = 0.006) in Gr-1 and Gr-2, respectively. RRA is an overtreatment in surgically ablated LR DTC patients. Successfully ablated RRA patients also had similar long-term outcome, however, those who failed, should be re-stratified as intermediate-risk category, and managed aggressively.