Complementary thyroidectomy results in patients with hemithyroidectomy and detection of multifocal papillary thyroid carcinoma

The primary treatment method for patients diagnosed with papillary thyroid cancer (PTC) is surgery, and there are differences in surgical options. There are authors who recommend supplementary thyroidectomy for PTC patients in the presence of multifocality, but it has not been reported as an absolute indication and is left to the physician's decision. Since supplementary thyroidectomy is a controversial issue, in this study we aimed to evaluate the histopathological, clinical and laboratory evaluation of the cases that underwent supplementary thyroidectomy and to examine its effects on their postoperative conditions. For this purpose, 146 patients who were diagnosed with multifocal PTC and who underwent hemithyroidectomy and were followed up at Trakya University Faculty of Medicine between 2005 and 2023 were investigated. 78.8% of the patients participating in our study were female, and the mean age of the patients was determined as 48.30±12.39 years. In the first operation, lymphocytic thyroiditis was detected in 44.5% of the thyroid tissue taken, capsular invasion was detected in 17.2%, while lymphovascular invasion was not detected in 97.9% and perineural invasion was not detected in 98.6%. Lymph node metastasis was not found in 96.7%, while tumor size was < 1 cm in 58.9% and 34.2% was found to be multifocal. When tumor variant was examined, follicular variant was seen in 45.9% and classical variant was seen in 31.5%. According to the pathology results of 146 patients who underwent hemithyroidectomy, 113 (77.4%) underwent completion thyroidectomy. In the group that underwent completion thyroidectomy, the frequency of Hashimoto thyroiditis, the frequency of anti-TPO positivity, the rate of tumor size greater than 1 cm, and the rate of tumor being multifocal were found to be significantly higher. In those who underwent completion thyroidectomy, malignancy was detected in 37.2% in the second pathology result. When the distribution of tumor variants in the pathology results of patients diagnosed with malignancy according to the second pathology result was examined, it was determined that 54.8% were follicular, 28.6% were classical, 9.5% were mixed, 4.8% were oncocytic and 52.4% were occult. When we evaluated the relationship between the variants in the two pathology results with Cohen's kappa test, the Kappa value was determined as 0.243 and was evaluated as low agreement. We believe that completion thyroidectomy is beneficial since the application of completion thyroidectomy to surgeries performed other than total thyroidectomy in papillary thyroid cancer will prevent overlooked malignancies in the opposite lobe or in the remaining residual thyroid tissue. Keywords: Papillary thyroid cancer, completion thyroidectomy, multifocality.