[111In-DTPA-D-Phe1]-octreotide scintigraphy in patients with hormone-refractory prostatic adenocarcinoma can predict therapy outcome with octreotide treatment: a pilot study.

A pilot study to evaluate the predictive value of Indium-111-labelled somatostatin analogue [DTPA-D-Phe1]-octreotide scintigraphy (OctreoScan111) in the Octreotide treatment of hormone-refractory prostatic adenocarcinoma was initiated. Ten patients were investigated with OctreoScan111 with regard to disease extension and tumor-to-background ratio. Subsequently, the patients were treated with Octreotide (Sandoz, Basel, Schweiz) at a dose of 100 micrograms twice a day subcutaneously. Three patients experienced symptomatic relief, and two of these responded with a decrease in PSA. Three patients did not notice any difference after 6 months of treatment and two of them developed an increase in their PSA value. One patient progressed after five months as regards both PSA and symptoms. Three patients were not able to complete treatment. Of the seven evaluable patients, the three with the highest tumour-to-background ratios at OctreoScan111 were those patients with reduced or stable PSA levels, and none of these progressed during treatment. Previous reports along with this study demonstrate that only a minority of patients with hormone-refractory prostatic adenocarcinoma benefit from Octreotide treatment. However, OctreoScan111 investigations may identify patients who will respond to Octreotide therapy.