Therapeutic efficiency of rhenium-188-HEDP in human prostate cancer skeletal metastases

Rhenium-188-HEDP (Re-188-HEDP) is a new and attractive radiopharmaceutical for the treatment of metastatic bone pain. As a product of W-188/Re-188 generator, it is convenient for clinical therapeutic use with a short physical half-life of 16.9 h and a maximal beta-energy of 2.1 MeV. We investigated the effect of Re-188-HEDP on pain relief, analgesic intake and impairment of bone marrow function in 27 patients with bone metastases induced from prostate cancer. All patients were interviewed using a standardised set of questions before, and after therapy for 12 weeks. The patients were treated with 2700-3459 MBq of Re-188-HEDP. Blood samples were taken weekly for 12 weeks, and a blood count was performed. Patients described an improvement on the Karnofsky performance scale from 74 +/- 7 to 85 +/- 9% 12 weeks after therapy (P = 0.001). The pain score showed a maximum decrease from 44 +/- 18 to 27 +/- 20% in the third to the eight week after therapy (P = 0.009). Seventy-six percent of the patients described a pain relief without increase of analgesic intake. Twenty percent of the patients could discontinue their analgesics and were pain free. Mean platelet count decreased from (286 +/- 75)*10(3) mul(-1) to (215 +/- 92)*10(3) mul(-1), and mean leucocyte count from (7.7 +/- 1.5)*10(3) mul(-1) to (6.0 +/- 1.9)*10(3) mul(-1) in the second to the fourth week after therapy. The maximal differences between the values of platelets and leucocytes before and after therapy were not statistically significant (P = 0.021 and 0.094). In conclusion, Re-188-HEDP is an effective radiopharmaceutical used in the palliative treatment of metastatic bone pain in prostate cancer and shows minimal bone marrow toxicity.