Endocrine Abstracts

Breast cancer (BC) is the most common type of cancer and the leading cause of cancer-related death in women worldwide. A considerable number of these long-term survivors may therefore have an elevated risk of developing a second primary malignancy (SPM). Thyroid cancer (TC) is the most prevalent endocrine malignancy among women. Epidemiologic studies have indicated that patients with BC have a higher risk of developing TC as an SPM, and vice versa, than would be expected in the general population; and the risk of BC following TC is increased by 21% to 89% and that of TC following BC by 31% to 73%. We present a female patient with left breast carcinoma operated about 20 years ago with no medical documentation, recently diagnosed (January 2022) with papillary thyroid carcinoma TNM (AJCC 8th edition): pT2N0LV0Pn0 invasive in thyroid capsule and also in strap muscle with postoperative Thyroglobulin level of 26.7 ng/ml which indicated radioiodine ablation with 3570,29 MBq. At whole body scintigraphy were described multiple pulmonary secondary lesions, although thyroglobulin level decreased to 16 ng/ml. Structural imaging confirmed pulmonary, hepatic, splenic and even bone secondary lesions. Because the thyroglobulin level was discordant with multiple distant metastasis, we also investigate breast tumor marker CA15-3 = 442.74 U/ml (normal value: 0-32.4 U/ml) and structural images showed right breast carcinoma (bilateral breast carcinoma) confirmed by biopsy. Particularity of this case report is that secondary lesions appeared despite decreasing thyroglobulin level. Could we assume breast origin metastasis on radioactive WBS scintigraphy considering that breast cancer has sodium-iodine symporter expression? Or we could suspect thyroid related secondary lesions with abnormal low thyroglobulin level. The patient had progression of metastasis at 6 months after the radioactive iodine treatment, even if the thyroglobulin level was almost undetectable (0.3 ng/ml) suggesting an excellent biochemical response after iodine treatment for thyroid cancer.