Efficacy of postoperative radioactive iodine therapy for patients with low and intermediate risk papillary thyroid carcinoma.

Purpose: This study aimed to evaluate the efficacy of postoperative radioactive iodine (RAI) and its impact on recurrence rates and survival benefits in low- to intermediate-risk papillary thyroid carcinoma (PTC).

Methods: This retrospective study involved the examination of 1286 patients diagnosed with low- to intermediate-risk PTC who underwent total thyroidectomy with or without neck dissection, supplemented with postoperative RAI therapy or not between the years 2000 and 2021.

Results: From the patient pool, 589 (45%) were classified as low-risk and 697 (55%) as intermediate-risk according to the 2015 American Thyroid Association guidelines. Among the low-risk group, 375 (63.7%) underwent postoperative RAI, while in the intermediate-risk group, 566 (82.2%) underwent the procedure. The overall survival and disease-free survival rates were not statistically different between the groups that received RAI and those that did not, in both the low- and intermediate-risk categories. In a subgroup analysis, within the intermediate-risk category, postoperative RAI was significantly correlated with decreased recurrence in two subgroups: patients over 55 years with pN1b disease (hazard ratio 0.043, 95% confidence interval 0.004-0.500, p = 0.012) and patients over 55 years with five or more metastatic lymph nodes (hazard ratio 0.060, 95% confidence interval 0.005-0.675, p = 0.023).

Conclusion: Our findings suggest that, while post-total thyroidectomy RAI does not substantially influence recurrence or survival rates in most low-risk and intermediate-risk PTC patients, it may be beneficial in specific subgroups, particularly patients over 55 with pN1b disease or those presenting with five or more metastatic lymph nodes.