Low-risk differentiated thyroid cancer and radioiodine remnant ablation: A systematic review of the literature

Background: Radioiodine remnant ablation (RRA) has traditionally been one of the cornerstones of differentiated thyroid cancer (DTC) treatment. The decision to use RRA in low-risk (LR) and intermediate-risk (IR) patients is controversial. The aim of this review is to examine the evidence of RRA benefit in the staging, follow-up, and recurrence prevention in LR and IR DTC patients. Methods: From a PubMed search, we selected original papers (OPs) using the following inclusion criteria: 1) DTC; 2) LR and IR patients; 3) non-RRA-treated patients or RRA-treated vs non-RRAtreated groups; 4) a report of the outcome of cancer recurrence; and 5) publication since 2008. Results: Neck ultrasonography is superior to whole-body scan for disease detection in the neck. A rising or declining serum thyroglobulin level over time provides an excellent positive or negative predictive value, respectively, even in non-RRA-treated patients. No OP demonstrating RRA benefit on recurrence in LR patients was found; two OPs found no evidence of benefit. We found 11 OPs that observed some benefit in reducing recurrence rates with RRA in IR patients and 13 OPs that failed to show benefit from RRA in this group. Conclusions: Neck ultrasonography and serum thyroglobulin measurement are equivalent or superior in detecting and localizing residual disease compared to post-therapy whole-body scan. There is no evidence of RRA benefit in recurrence prevention for LR patients. There are conflicting data on IR patients and only a few studies with homogenous and properly stratified populations. A careful evaluation of tumor pathological features and patient characteristics and preferences should guide RRA decision making.