Purpose: The activity of estramustine phosphate is synergistic with paclitaxel against hormone refractory prostate cancer. Moreover, the single agent activity of carboplatin has demonstrated a 17% response rate in measurable disease. Therefore, we conducted a prospective trial to establish more effective chemotherapy consisting of paclitaxel, estramustine phosphate and carboplatin for hormone refractory prostate cancer.
Materials and methods: The study included 32 patients with hormone refractory prostate cancer. Prior chemotherapy was accepted. Patients were treated with 100 mg./m.2 paclitaxel intravenously weekly, 10 mg./kg. estramustine phosphate orally daily and carboplatin intravenously to an area under the curve of 6 on day 1 of every 4-week cycle. Treatment was continued until disease progression or excessive toxicity.
Results: Of the 32 patients 30 were assessable for response. A median of 7 consecutive cycles was administered per patient. Ten patients had received prior cytotoxic chemotherapy. Levels of prostate specific antigen decreased by greater than 50% in 100% of patients and by greater than 90% in 56.7%. Partial response was obtained in 61.1% of measurable lesions. Consumption of medication for cancer induced pain was reduced in 89.5% of patients. Tumor volume reduction and/or antitumor therapeutic effects were exhibited in 81.0% of patients with positive biopsy. At a median followup of 48 weeks median time to progression was 48 weeks and median overall survival was 95 weeks. Two patients suffered myocardial infarction and hepatic insufficiency, respectively, and discontinued treatment during the first cycle. Major toxicities were grade 3 or 4 anemia in 59.4% of patients, leukopenia in 37.5%, thrombocytopenia in 28.1% and neuropathy in 12.5%. However, all toxicity was temporary and reversible with dose reduction or temporary cessation of chemotherapeutic agents.
Conclusions: Paclitaxel, estramustine phosphate and carboplatin chemotherapy was extremely effective for hormone refractory prostate cancer. Although hematological and neurotoxicity were modest, this therapy may be more manageable with lower doses.