PRRA Fails to Improve Long-Term Outcomes in Low-Risk Papillary Thyroid Cancer

Postoperative radioiodine remnant ablation (PRRA) does not improve long-term outcomes compared with curative bilateral thyroid lobar resection (BTLR) among patients with low-risk adult papillary thyroid carcinoma (PTC), according to a study presented at the 88th Annual Meeting for the American Thyroid Association in Washington, D.C.¹

The use of PRRA has risen across the world since a 1977 report asserted that it reduces tumor recurrence. The aim of this study was to evaluate long-term outcomes of PRRA among patients with low-risk PTC with a postoperative MACIS score less than  6.

The single-institution study included a total of 2740 patients from 3 time periods: 1967 to 1976, 1977 to 1986, and 1987 to 2016. PRRA was used in 8%, 51%, and 32% of patients during these time periods, respectively. The study end points were cause-specific mortality (CSM) and tumor recurrence.

PRRA failed to improve 20-year CSM or recurrence and, during some time periods, significantly increased these rates. The CSM and tumor recurrence rates during 1977 to 1986 were 0% and 5%, respectively, compared with 0.5% and 9% with BTLR alone (P > .8). CSM and TR rates were 1.8% and 13%, respectively, with PRRA compared with 0.7% (P = .34) and 6% (P = .02) with BTLR alone during 1977 to 1986. Similarly, during 1987 to 2016, the CSM and TR rates were 0.7% and 20.5% with PRRA compared with 0% (P = .11) and 9% (P < .001) with BTLR alone.

There was no difference in local recurrence rates with the use of PRRA compared with BTLR alone among patients with N0 disease. Patients with N1 disease, however, experienced significantly higher 20-year rates of local recurrence with PRRA at 28% compared with 16% among patients who underwent BTLR alone (P = .004). There was no difference in distant spread between groups.

The authors stated that these results suggest that PRRA did not reduce CSM or tumor recurrence in this population. “These results therefore provide a strong basis for not recommending PRRA in the 85% of adult PTC patients who have MACIS scores < 6 and who have undergone BTLR ‘with curative intent’,” they wrote.

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Reference

1. Hay I, Johnson T, Kaggal S, Reinalda M, Goellner J. The ‘rise and fall’ of postoperative radioiodine remnant ablation (PRRA) in 2,740 MACIS <6 low-risk adult papillary thyroid carcinoma (LRAPTC) patients definitely treated at one institution during five decades: did PRRA ever significantly diminish cause-specific mortality (CSM) or tumor recurrence (TR) rates after potentially curative bilateral thyroid lobar resection (BTLR) and selective removal of regional metastases? Presented at: the 88th Annual Meeting of the American Thyroid Association; Washington, D.C.: October 3-7, 2018.