Second adjuvant radioiodine therapy after reoperation for locoregionally persistent or recurrent papillary thyroid carcinoma

Differentiated thyroid carcinoma (DTC) has increased incidence. Intermediate- and high-risk patients have lymph node relapse rate ranging from 10 to 50%, and receive multiple reinterventions, increasing the morbidity of the disease. Currently, there are no established guidelines for the use of second radioactive iodine (RAI) therapy after the reintervention for local recurrence. This is a retrospective review of the medical records of 1,299 patients treated from January 2016 to July 2019 with DTC. We included 48 patients who received total thyroidectomy, RAI remnant ablation, surgery to remove the locally recurrent/persistent papillary thyroid carcinoma (PTC), and received a second RAI therapy. There were no significant differences between thyroglobulin (Tg) levels before reoperation (Tg0), Tg levels postoperatively (Tg1), and Tg levels after 6 months of second adjuvant RAI therapy (Tg2). However, we evidenced a 69.79% drop in first Tg levels (Tg0: 24.7 vs. Tg1: 7.56, p=0.851) and 44.4% decrease in second Tg levels (Tg1: 7.56 vs. Tg2: 4.20, p=0.544). Also, 77.1% of the patients did not have another documented recurrence. The median relapse-free time was 10.9 months (range: 1.3–58.2 months). The results of the study cannot assess that a second RAI treatment after reoperation for locoregionally persistent or recurrent disease have a significant impact on treatment outcomes in intermediate- or high-risk patients with PTC. However, the 77.1% of patients have not presented a second documented recurrence and the median values of Tg and TgAb levels showed a substantial decrease after surgery and second RAI treatment. (author)