Intraoperative radiotherapy during radical prostatectomy for locally advanced prostate cancer: technical and dosimetric aspects.

PURPOSE: To analyze the feasibility of intraoperative radiotherapy (IORT) in patients with high-risk prostate cancer and candidates for radical prostatectomy. METHODS AND MATERIALS: A total of 38 patients with locally advanced prostate cancer were enrolled. No patients had evidence of lymph node or distant metastases, probability of organ-confined disease >25%, or risk of lymph node involvement >15% according to the Memorial Sloan-Kettering Cancer Center Nomogram. The IORT was delivered after exposure of the prostate by a dedicated linear accelerator with beveled collimators using electrons of 9 to 12 MeV to a total dose of 10-12 Gy. Rectal dose was measured in vivo by radiochromic films placed on a rectal probe. Adminstration of IORT was followed by completion of radical prostatectomy and regional lymph node dissection. All cases with extracapsular extension and/or positive margins were scheduled for postoperative radiotherapy. Patients with pT3 to pT4 disease or positive nodes received adjuvant hormonal therapy.
RESULTS: Mean dose detected by radiochromic films was 3.9 Gy (range, 0.4-8.9 Gy) to the anterior rectal wall. The IORT procedure lasted 31 min on average (range, 15-45 min). No major intra- or postoperative complications occurred. Minor complications were observed in 10/33 (30%) of cases. Of the 27/31 patients who completed the postoperative external beam radiotherapy, 3/27 experienced Grade 2 rectal toxicity and 1/27 experienced Grade 2 urinary toxicity.
CONCLUSIONS: Use of IORT during radical prostatectomy is feasible and allows safe delivery of postoperative external beam radiotherapy to the tumor bed without relevant acute rectal toxicity. Copyright 2010 Elsevier Inc. All rights reserved.