Evaluation of thyroid cancer patients with Ga-68 DOTA-TATE PET/CT: Initial experience at a tertiary health care centre

Objectives To determine the role of Ga-68 DOTA-TATE PET/CT in identifying Non-Iodine avid/ non-FDG avid disease in patients with Differentiated Thyroid Cancer (DTC) and in the post-surgical assessment/monitoring of patients with Medullary Thyroid Carcinoma (MTC).

Methods A total of 17 patients of thyroid cancer (8 DTC and 9 MTC) were subjected to Ga-68 DOTA-TATE PET/CT scanning for the detection of metastatic disease. The results of the Ga-68 DOTA-TATE scans were correlated with final diagnosis arrived at by surgery, histopathology, biochemistry and/or clinical examination.

Results All 8 DTC patients had raised serum Thyroglobulin (TG) and negative FDG PET/CT scans. Five out of 8 patients revealed DOTA-TATE avid disease. Depending on their clinical status, 2 received PRRT, 2 chemotherapy and 1 radiotherapy. Three had negative DOTA scans. Two out of these three had non-DOTA-TATE avid extensive pulmonary metastases and were subjected to chemotherapy. One, whose DOTA scan was negative, did not reveal any disease either on FDG PET or Ga DOTA-TATE, except for a slight rise in TG; he is now on follow up over a period of 2 years with decreasing TG levels. Four out of 9patients of MTC revealed positive DOTA-TATE scans (TP), all had raised calcitonin; one had surgical resection and one received radiotherapy, the rest are on clinical follow up. Five patients had negative DOTA-TATE scans, in 2 calcitonin levels were normal (True negative); there were three false negative studies. Sensitivity, specificity and accuracy of DOTA-TATE scans in detecting somatostatin receptor expressing disease in MTC were found to be 57, 100 and 66% respectively.

Conclusions A significant proportion of Thyroid Cancer patients (in our case 54%) may demonstrate somatostatin receptor expressing disease. Such patients may benefit from surgery, radiotherapy or PRRT depending on the extent and severity of their disease.