Incidental thyroid nodules (ITN) are detected in 1% in women with malignancy risk of 7-15%. Therefore, at least follow-up of ITN is important. FDG uptake of thyroid gland is seen in 2-3% of PET-CT scans. Thirty-five - 40% of incidental nodules with FDG uptake were evaluated as malignant in further examinations. Breast and thyroid cancers are two of the mostly seen cancers in women among the World. This study presents how incidental thyroid nodules were managed in breast cancer patients under medical oncology follow-up.

A thousand and hundred two patients who were operated on breast cancer between 2019-2023 were assessed retrospectively. Patients with prior known thyroid condition were excluded. Patient data were examined retrospectively from the hospital system.

Seven hundred and one (63.6%) of 1102 breast cancer patients had information about thyroid gland in PET-CT reports. Patients with prior history of thyroid disease (n=312, 44.5%) were excluded. In 35 (3.9%) of the remaining 389 cases there were abnormal FDG uptake in thyroid gland (n=19, 54.3% malignant uptake, two were developed under chemotherapy). Only three (15.8%) of 19 underwent ultrasound and biopsy, which resulted papillary carcinoma both with biopsy and operation.

As a result, thyroid pathologies detected in PET-CT scan done for breast cancer follow-up are not very rare. However, these nodules do not meet enough attention by medical oncologists. Therefore, a statement can be published after prospective observational study.