Purpose: The aim of this phase II study was to evaluate the tumour response of neuroendocrine tumours to targeted irradiation with the radiolabelled somatostatin analogue 90Y-DOTATOC. In addition, the palliative effect of 90Y-DOTATOC treatment on the malignant carcinoid syndrome and tumour-associated pain was investigated.
Patients and methods: Forty-one patients (mean age 53 years) with neuroendocrine gastroenteropancreatic and bronchial tumours were included. Eighty-two percent of the patients had therapy resistant and progressive disease. The treatment consisted of four intravenous injections of a total of 6000 MBq/m2 90Y-DOTATOC, administered at intervals of six weeks.
Results: The overall response rate was 24%. For endocrine pancreatic tumours it was 36%. Complete remissions (CR) were found in 2% (1 of 41), partial remissions (PR) in 22% (9 of 41), minor response in 12% (5 of 41), stable disease (SD) in 49% (20 of 41) and progressive disease (PD) in 15% (6 of 41). The median follow up was 15 months (range 1 month to 36 months). The median duration of response has not been reached at 26 months. The two-year survival time was 76 +/- 16%. Eighty-three percent of the patients suffering from the malignant carcinoid syndrome achieved a significant reduction of symptoms. The treatment was well tolerated. A reduction of pain score was observed in all patients (5 of 41) with morphine dependent tumour-associated pain. Side effects included grade III (NCIGC) pancytopenia in 5%, and vomiting shortly after injection in 23%. No grade III-IV renal toxicity was observed.
Conclusion: Targeted radiotherapy with 90Y-DOTATOC is a novel, well-tolerated treatment for neuroendocrine tumours with a remarkable objective response rate, survival time, and symptomatic response.