Objective: In this study, we aimed to evaluate the tumor size for proximal and distant metastases when the new and old TNM classification is taken into account in differentiated thyroid cancers.
Material and methods: Two hundred sixty eight patients diagnosed with thyroid carcinoma, undergoing bilateral total or subtotal thyroidectomy treated with high doses of I-131 were examined retrospectively. The data of these patients were compared after classification, according to tumor size <1 cm and <2 cm, lymph node metastases thyroid and tumor capsule invasion at the time of diagnosis, and accumulation of abnormal activity in post I-131 treatment whole-body scan. I-131 uptakes besides physiological and thyroid bed were considered as abnormal activity uptakes.
Results: A total of 268 patients with average age of 19-82 yrs (mean: 47.0±13.8 yrs) were included in the study. At postoperative histopathological evaluation, 228 (85.1%) of patients were reported as papillary, 13 (4.9%) as follicular, 23 (8.6%) as well differentiated tumor of unknown malignant potential, 2 (0.7%) as insular and 2 (0.7%) as Hürthle-cell carcinoma. In patients with known tumor size, 96 of 207 (46.4%) patients' tumor size was <1 cm and in 111 (53.6%) >1 cm. In the same group, according to the revised TNM classification, in 149 of 207 patients (72%) the tumor size was <2 cm, whereas in 58 (28%) >2 cm. Of 187 patients with negative lymph nodes, 15 (8%) showed abnormal activity accumulation in the first post I-131 treatment whole-body scan and 10 (40% of 25 patients) positive lymph node (p<0.05) involvement.
Conclusion: Since the treatment of patients with microcarcinoma is controversial, tumor size should not be the only factor considered in patients with differentiated thyroid cancer Tissue tumor invasion, age, gender and multifocality should also be taken into account.
Conflict of interest: None declared.
Keywords: I-131; TNM classification; differentiated thyroid carcinoma; microcarcinoma.