Aim: We aimed to assess the recurrence rates of papillary thyroid microcarcinoma in patients with and without histopathological risk factors after radioiodine (RAI) ablation treatment.
Materials and methods: A total of 357 papillary thyroid microcarcinoma patients who were referred to Ankara University Medical School, Department of Nuclear Medicine for RAI ablation treatment after total or near-total thyroidectomy were included in the study. All patients received RAI ablation treatment 4-6 weeks after surgery. After RAI ablation, patients were monitored every 3 months within the first 6 months and then every year.
Results: During follow-up, sixth-month iodine-131 (I-131) whole-body scans showed successful ablation in 333 (93.3%) patients. However, one (0.2%) patient had a focal lung uptake on the sixth-month I-131 whole-body scan, although the postablative scan gave no evidence of lung metastasis. Lung metastasis of this patient was treated with a second dose of RAI. The mean follow-up period was 124 (min-max: 6-216) months. No recurrence was detected in 344 (96.3%) patients during the follow-up period. However, in 13 (3.6%) patients, new recurrence or metastasis had developed. Lymph node metastasis was detected using fluorine-18 flourodeoxyglucose PET/computed tomography in four and using neck ultrasound in eight of them. The metastasis rates of patients with papillary microcarcinoma at a single focus with no thyroid capsule or lymphovascular invasion (n=268) and those of patients with thyroid capsule and/or lymphovascular invasion (n=89) were compared. Metastasis was seen in six and seven patients in those groups, respectively. The difference in metastasis rate between the two groups was statistically significant (2.2 vs. 9.2%, P=0.008).
Conclusion: RAI ablation is beneficial in the management of papillary thyroid microcarcinoma patients with histopathological risk factors. It also improves the sensitivity of thyroglobulin and antithyroglobulin, facilitating easier and safer follow-up.