Incidental thyroid malignancies in patients operated for hyperthyroidism

This study aimed to investigate the frequency of incidental thyroid cancer in patients undergoing thyroidectomy due to different forms of hyperthyroidism and also explore the behavioral pattern of cancer in malignant cases.
A total of 1210 patients operated in the clinic between March 2014 and August 2018 were screened consecutively. Of these, 347 were thyrotoxic; 68.9% were female, and 31.1% were male. Further, 43.8% (n = 152) had Graves’ disease (GD), 4% (n = 14) had toxic nodular goiter (TNG), and 52.2% (n = 181) had toxic multinodular goiter (TMNG). Patients with hyperthyroidism were classified into two groups (Group 1: Benign; Group 2: Malignant). Data including age, sex, presence of GD, body mass index (BMI), thyroid volume, thyroid-stimulating hormone value at the time of diagnosis, TR-Ab, anti-TPO-Ab, and follow-up of hyperthyroidism were compared between the groups.
Thirty-eight (11%) of all thyrotoxic patients had thyroid carcinoma. Sixteen (10.52%) patients with GD, 2 (14.3%) with TNG, and 20 (11%) with TMNG had thyroid carcinoma. The histopathological examination revealed 35 papillary (21 microscopic), 1 follicular, and 2 cases of medullary thyroid carcinoma. The incidence of malignancy increased in patients with high BMI. Anti-TR-Ab and anti-TPO antibodies were found to be significantly higher in the malignant group.
The risk of developing thyroid cancer in different forms of hyperthyroidism is similar. Even in thyrotoxic patients, high BMI correlates with the development of thyroid cancer. It is believed that the cancer rate of 11% should not be underestimated. It is strongly recommended that toxic patients, especially patients with TNG, be closely monitored with USG and FNAC for possible malignancy development.