Octreotide scintigraphy and Chromogranin A do not predict clinical response in patients with octreotide acetate-treated hormone-refractory prostate cancer

In this pilot study, the predictive value of Octreotide scintigraphy (Octreoscan) and/or Chromogranin-A (CgA) was investigated in patients with hormone-refractory prostate cancer treated with Octreotide acetate. In total, 20 patients with progressive disease and bone metastases entered the trial. At baseline Octreoscan, CgA, PSA, alkaline phosphates (ALP) and two self-administered questionnaires (EORTC QLQ C-30 (v3) and brief pain index) were performed and a diary of the pharmaceutical was started. The treatment consisted of Octreotide (Sandostatin LAR) acetate 30 mg intramuscular injection every month. The blood samples and questionnaires were repeated every month until 3 months. Clinical responder was defined as a patient with increased global health score more than 10 units and stable or decreased pain score without an increase in analgesic. In all, 17 patients were treated per protocol, and four were assessed as clinical responders. Six patients developed a reduction in ALP (median -26%, range -5 to -78%). All patients increased in PSA. At baseline, three patients had a negative Octreoscan and the patients with positive lesions, demonstrated uptake of low intensity. At baseline the CgA was elevated above the normal range in 15 of the patients, and during treatment five patients decreased their CgA to the normal range. Neither baseline Octreoscan nor CgA could identify the clinical reponders. A minority of patients improves their health-related quality of life. The decrease and normalization of CgA levels in five patients during therapy indicates therapeutic activity but Octreoscan and CgA could not identify clinical responders.