Polyamine-reduced diet in metastatic hormone-refractory prostate cancer (HRPC) patients

Polyamine (PA) deprivation is effective in prostate carcinoma models. We have assessed the observance by patients, tolerance and side effects of a PA-reduced diet (PRD) and intestinal decontamination (ID), in order to reduce PA dietary and intestinal bacterial pools, in metastatic, hormone-refractory prostate cancer (HRPC) patients. A total of 13 volunteers (mean age, 67±10 years) with metastatic HRPC were proposed for PRD and ID (0.75 g/day of oral neomycin every other week). The mean time from HRPC diagnosis to the start of the diet was 12±8 months. Of the total 13, seven patients had received prior chemotherapy or Estramustine phosphate. PRD was obtained after HPLC assessment of PA contents in current foods and given 5 days a week. Toxicity, performance and pain status were assessed according to the World Health Organisation and EORTC scales. Prostatic specific antigen (PSA), blood counts, ionograms, transaminases and erythrocyte PA spermidine (Spd) and spermine (Spm; assessed by HPLC) were evaluated regularly. Mean observance was 8±7 months (range, 2–26 months). One case of grade II toxicity to neomycin was observed. Cancer-specific survival (after the diet) was 14±7 months, and two patients are still alive. All the other patients have died of their cancer at 12±6 months (range, 4–20 months). Cancer-specific survival after hormonal escape was 27±11 months (range, 9–45 months). Performance status was improved during the regimen and deteriorated 3 months after stopping. Pain score was improved (1.3 versus 0.6; P=0.04) during the diet and increased (2.1 versus 0.3) 3 months after stopping. Erythrocyte Spd (11.6±7 versus 7.7±2 nmol/8×10⁹ erythrocytes; P=0.036) and Spm (7±6 versus 3.9±1.6 nmol/8×10⁹ erythrocytes; P=0.036) levels were significantly reduced at 3 months. One patient had a >50% reduction in PSA, three patients had PSA stabilization for 6 months. PSA progression was observed in all other patients. No significant modification of other studied biological parameters was noted. Reducing PA dietary intake and ID is a well-observed and tolerated regimen and seems to be beneficial for patient quality of life and pain control. Patients with low initial PSA can experience durable stabilization. These encouraging results in such an aggressive disease certainly warrant further investigation.