The palliative role of 131I-MIBG and 111In-octreotide therapy in patients with metastatic progressive neuroendocrine neoplasms.

Background: Radiolabeled octreotide and metaiodobenzylguanidine (MIBG) have demonstrated limited antitumor effect on neuroendocrine neoplasms (NENs). The purpose of this study was to assess the palliative benefit of radionuclide therapy (RNT) in NENs.

Methods: Since April 2001, RNT for progressive, nonsurgically resectable NENs was utilized. NENs that were MIBG positive received 131 I-MIBG therapy, whereas octreotide-only-positive neoplasms received 111 In-octreotide therapy. Symptomatic, quality of life (QoL), biochemical, and radiographic responses to RNT were evaluated.

Results: Twenty-four patients had either MIBG or octreotide avid NENs. A mean (range) of 4 (1-7) 131 I-MIBG treatments were given to 13 patients over a duration of 18 months (6-42). The group consisted of 2 medullary thyroid cancer (MTC), and 2 foregut and 9 small-bowel carcinoids; 12 patients (92%) had symptomatic improvement. Stability of tumor size was confirmed in 6, regression in 2, and progression in 5. Biochemical responses were demonstrated in 2. Five (2-16) treatments of 111 In-octreotide was given to 11 patients over 17 months (6-40). There were 1 MTC, 1 insulinoma, 2 gastrinomas, and 3 small-bowel and 4 foregut carcinoids. Symptomatic benefit was seen in 6 (55%), biochemical response in 3. Tumor regression was seen in 1, stability in 5, and progression in 5.

Conclusions: Radionuclide therapy appears to offer good palliation to patients with progressive NENs.