Comparison of preplanning and intraoperative planning for I-125 prostate brachytherapy

Objective: To compare two widely used permanent prostate brachytherapy techniques, preplanning and intraoperative planning, based on postimplant dosimetry, toxicity and biochemical outcomes. Methods: Between 2003 and 2006, 665 men with localized prostate cancer were treated with permanent interstitial implantation. The first 227 consecutive men were treated with the preplanning technique, followed by 438 men treated with the intraoperative technique. Late toxicity was scored by the Common Terminology Criteria for Adverse Events v.4.0. Biochemical failure was defined as a prostate-specific antigen increase of more than 2 ng/ml above the nadir value excluding a benign bounce. Univariate and multivariate analyses were performed to identify the variables associated with biochemical failure-free survival. Results: Postimplant target coverage was similar in the two groups, with a small difference in risk organ doses. Mean V100 was 96.3 vs. 96.7% (P = 0.205), D90 was 119.6 vs. 119.4% (P = 0.884), urethral D10 was 157.5 vs. 146.1% (P = 0.010), rectal V100 was 0.57 vs. 0.43 cc (P = 0.002) in the preplanning and intraoperative planning groups, respectively. Acute and late Grade 3 genitourinary and gastrointestinal toxicities were , <1% for both methods. The 5-year biochemical failure-free survival rate was 95.4% for the preplanning and 94.0% for the intraoperative planning group (P = 0.776). Multivariate analysis revealed Gleason score, biopsy positive rate and V100 to be predictors of biochemical failure-free survival, while the planning technique was not significant. Conclusion: This large-scale analysis of high-quality implants revealed similar postimplant dosimetry, toxicity profiles and biochemical failure-free survival for the preplanning and intraoperative planning methods.