Association of Radioactive Iodine Administration After Reoperation With Outcomes Among Patients With Recurrent or Persistent Papillary Thyroid Cancer.

Importance: One-third of patients with papillary thyroid cancer (PTC) develop persistent or recurrent disease after initial therapy. Most patients with persistent or recurrent disease undergo reoperation, but the role of treatment with radioactive iodine (RAI) after reoperation is unclear. Objective: To determine whether receipt of RAI after reoperation for recurrent PTC is associated with improved outcomes. Design, Setting, and Participants: This retrospective cohort study included electronic health record data from 102 patients who underwent neck reoperation for persistent or recurrent PTC at a tertiary referral center from April 2006 to January 2016; 50 patients received RAI after reoperation, and 52 did not receive RAI after reoperation. Data analysis was performed from September 1, 2017, to December 1, 2017. Main Outcomes and Measures: Suppressed thyroglobulin (Tg) levels were compared between patients who underwent reoperation and received RAI and patients who underwent reoperation without receipt of RAI at the following time points: before reoperation (Tg0), after reoperation (Tg1), and after RAI or a comparable time interval among patients whose cases were managed without RAI (Tg2). Outcomes were biochemical response and structural recurrence after reoperation.
Results: The cohort comprised 102 patients who underwent neck reoperation for persistent or recurrent PTC (median age, 44 years [interquartile range, 33-54 years; SD, 14 years]; 67 [66%] female), 50 of whom received treatment with RAI after reoperation. Clinicopathologic characteristics of the patients at the time of the initial surgical procedure were similar between the reoperation with RAI group and the reoperation without RAI group with the exception of tumor (T) stage (T3 and T4, 28 of 50 [56%] vs 19 of 52 [37%]). Although median Tg levels were similar between the reoperation with RAI group and the reoperation without RAI group (Tg0, 3.3 ng/mL vs 2.4 ng/mL; Tg1, 0.6 ng/mL vs 0.2 ng/mL; and Tg2, 0.5 ng/mL vs 0.2 ng/mL; all differences were nonsignificant), the rate of excellent response at Tg1 was lower in the reoperation with RAI group (4 of 33 [12%] vs 24 of 51 [47%]; P = .007). Structural recurrence after reoperation occurred in 18 of 50 patients (36%) in the reoperation with RAI group and 10 of 52 patients (19%) in the reoperation without RAI group. In multivariable analysis accounting for clinicopathologic characteristics and Tg0, receipt of RAI after reoperation was not associated with the rate of a second structural recurrence. In subset analyses limited to patients with incomplete response to reoperation and patients with T3 or T4 tumors, no association between receipt of RAI and the risk of a second recurrence was found. Conclusions and Relevance: Patients who received RAI after reoperation had outcomes similar to those in patients who underwent reoperation alone. RAI after reoperation was not associated with a significant clinical benefit in this limited series. Larger multicenter studies are required to determine whether receipt of RAI after reoperation improves outcomes among patients with recurrent PTC.