Successful surgical removal of occult metastases of medullary thyroid carcinoma recurrences with the help of immunoscintigraphy and radioimmunoguidedsurgery

Patients with recurrent or metastatic medullary thyroid carcinoma (MTC) wer e referred for pretargeted immunoscintigraphy (Affinity Enhancement System; AES) and radioimmunoguided surgery (RIGS). Data collected from 13 patients establish that whole-body AES immunoscintigraphy revealed metastases <360 mg and RIGS detected micrometastases (5-15 mg). All tissue samples removed by the surgeon were diagnosed by histology and immunohistochemistry of calc itonin to check the accuracy of IS and RIGS results. AES immunoscintigraphy is very sensitive, Of 34 metastases or recurrences detected, 22 had escape d physical examination or conventional imaging. The accuracy of RIGS was 86 %, its sensitivity 75%, and its specificity was 90% (n: = 208), IS and RIGS detected occult tumors that would have escaped surgery, clearly demonstrat ing clinical benefit. Serum calcitonin (normal, 10 pg/ml) and carcino-embry onic antigen (normal, 5 ng/ml) of two patients were restored to normal. In patients whose tumors were discovered, progression of their disease was slo wed, as evidenced by the large decrease in serum calcitonin and carcinoembr yonic antigen, an important prognostic factor. Surgery was canceled in one case where IS detected distant metastases out of surgical reach. Thus, AES immunoscintigraphy and RIGS might be of valuable help for the surgical mana gement of medullary thyroid carcinoma.