Post-surgical thyroid ablation in intermediate risk-differentiated thyroid cancer patients

Recently, Castagna et al. (1) compared ablation using a low (30–50 mCi, nZ85) vs high (R100 mCi, nZ140) I activity in differentiated thyroid carcinoma patients at intermediate risk of recurrence (T3, N1, or aggressive histological subtype) and showed the same efficacy. The authors concluded that, similar to low-risk patients, this group can also be treated with low I activity. However, a finding that calls attention is the low efficacy of ablation obtained in that study (1). Only 60% of the patients achieved complete remission in the first assessment after ablation; metastases were documented in 21% of those receiving 30–50 mCi and in 25.7% receiving R100 mCi on that occasion. These rates are surprising, especially when considering that 34 and 27.5% of the patients respectively had undetectable Tg already before ablation. It is possible to infer that, among patients with detectable Tg before ablation, complete remission was achieved in less than half. Since no comment on this finding was made in the discussion of the article, it is possible to interpret these results differently and to draw a conclusion that is completely opposite to that of the authors’. Instead of concluding that 30–50 mCi is effective in intermediate risk patients because the results were similar to those obtained with 100 mCi, one may conclude that, in intermediate risk patients with detectable Tg before ablation who account for 2/3 of cases, even 100 mCi failed to produce