Phase I study of concurrent weekly docetaxel, high-dose intensity-modulated radiation therapy (IMRT) and androgen-deprivation therapy (ADT) for high-risk prostate cancer

OBJECTIVE To evaluate in a phase I trial, the feasibility of adding concurrent weekly docetaxel chemotherapy to high-dose intensity modulated radiation therapy (IMRT) and androgen-deprivation therapy (ADT) for treatment of high-risk prostate cancer. PATIENTS AND METHODS Patients with high-risk prostate cancer were treated with a luteinising hormone-releasing hormone agonist (starting 2-3 months before IMRT and lasting 2 years), IMRT of 78 Gy to the prostate and seminal vesicles, and weekly docetaxel during RT. All patients had computed tomography and bone scans to exclude metastatic disease. A standard 3 + 3 design was used for docetaxel dose escalation. Successive patients were treated on dose levels of 10, 15, and 20 mg/m(2) of weekly docetaxel. RESULTS In all, 18 patients participated in the study: 15 (83%) had Gleason 8-10 disease; the other three had either clinical T3 disease and/or a prostate-specific antigen (PSA) level of >20 ng/mL. Grade 3 diarrhoea (a defined dose-limiting toxicity, DLT) occurred in one patient in each of the first two dose levels. However, when the cohorts were expanded, no further DLT was seen. Weekly docetaxel at 20 mg/m(2) (dose level 3) was successfully given without DLT. No patient had grade 4 or 5 toxicity. At a median follow-up of 2.2 years, all patients achieved a PSA nadir of <1 ng/mL, including 13 patients who had an undetectable PSA level. The 2-year biochemical progression-free survival was 94%. CONCLUSION A dose of 20 mg/m(2) of weekly docetaxel given concurrently with high-dose IMRT and ADT appears safe for further study in patients with high-risk prostate cancer.