Phase I-II study of intraoperative radiation therapy (IORT) after radical prostatectomy for prostate cancer

Purpose: Recent studies have suggested an alpha/beta ratio in prostate cancer of 1.5-3 Gy, which is lower than that assumed for late-responsive normal tissues. Therefore the administration of a single, intraoperative dose of irradiation should represent a convenient irradiation modality in prostate cancer. Materials and Methods: Between February 2002 and June 2004, 34 patients with localized prostate cancer with only one risk factor (Gleason score >= 7, Clinical Stage [cT] >= 2c, or prostate-specific antigen [PSA] of 11-20 ng/ mL) and without clinical evidence of lymph node metastases were treated with radical prostatectomy (RP) and intraoperative radiotherapy on the tumor bed. A dose-finding procedure based on the Fibonacci method was employed. Dose levels of 16, 18, and 20 Gy were selected, which are biologically equivalent to total doses of about 6080 Gy administered with conventional fractionation, using an alpha/beta ratio value of 3. Results: At a median follow-up of 41 months, 24 (71%) patients were alive with an undetectable PSA value. No patients died from disease, whereas 2 patients died from other malignancies. Locoregional failures were detected in 3 (9%) patients, 2 in the prostate bed and 1 in the common iliac node chain outside the radiation field. A PSA rise without local or distant disease was observed in 7 (21%) cases. The overall 3-year biochemical progression-free survival rate was 77.3%. Conclusions: Our dose-finding study demonstrated the feasibility of intraoperative radiotherapy in prostate cancer also at the highest administered dose. (C) 2008 Elsevier Inc.