Nuclear medicine in the detection, staging and treatment of gastrointestinal carcinoid tumours

111Indium-DTPA-octreotide has been used as the first tumour-targeted treatment, with rather low response rates (in the order of 10-20%) and no significant tumour shrinkage. The second radioactive analogue which has been applied in the clinic is 90yttrium-DOTA-Tyr3-octreotide, which has given partial and complete remissions in 20-30% of patients. The most significant side-effects have been kidney dysfunction, thrombocytopenia and liver toxicity. The most recent compound is 177lutetium-DOTA-Tyr3-octreotate, which has been applied by the Rotterdam group and has been reported to give partial remission in about 40% of the patients. In the near future, combined treatment with both 90yttrium and 177lutetium coupled to a somatostatin analogue might come into clinical trials. 177Lutetium may be more effective for smaller tumours whereas 90yttrium may be more effective for larger tumours.