Abstract
14606 Background: Transrectal Ultrasound (TRUS) guided interstitial implant for prostate cancer using High Dose Rate (HDR) + External Beam Radiation Therapy (EBRT) or IMRT has been reported with favorable results. The role of supplemental EBRT or IMRT in brachytherapy is undefined. We compare our results of HDR + IMRT vs. HDR monotherapy. Methods: Between 1997 and 2006, 276 patients with T1 and T2 localized prostate underwent TRUS interstitial implant. After discussion of treatment options, 109 patients elected HDR Implant + IMRT and 167 patients underwent HDR alone. No patient received Hormonal Blockade. Median Gleason Score was 7 (range: 4 to 10). Median PSA was 9.8 (0.60 to 39.8). In patients who received IMRT + HDR, 4500 cGy in 25 fractions was given via IMRT and 1650 cGy in 3 fractions via HDR. Our protocol for HDR alone, has called for two HDR Implants. The treatment volume received 2,250 cGy in 3 fractions prescribed to the 100% Isodose line, given over 24 hours. A 2nd implant was performed 4 weeks later, delivering a further 2,250 cGy in 3 fractions, bringing the final dose to the prostate to 4,500 cGy in 6 fractions. Results: There was no significant difference between the treatment groups with respect to T-Stage, Gleason Score, and PSA. With a median follow-up of 66 months (range: 6 months to 120 months), the overall PSA disease free survival (DFS) was 89.5% (247/276). In patients undergoing IMRT + HDR, PSA DFS was 89.0% (97/109) vs. 89.8% (150/167) for patients undergoing HDR alone (p = 0.6). The 5 year actuarial survival was 86% for the group receiving IMRT + HDR vs. 89% with HDR (log rank = 0.5). Urinary stress incontinence has occurred in 2.5% (7/276). RTOG late bladder toxicities were: 0% Grade 4, 0% Grade 3, and 3.3% (9/276) Grade 2. RTOG late rectal toxicities were: 0.4% (1/276) Grade 4, 0% Grade 3, 3.6% (10/276) Grade 2, and 4.7% (13/276) Grade 1. RTOG late rectal toxicity was higher in patients undergoing HDR + IMRT with 14.7% (16/109) of patients experiencing Grade 2 and 1 symptoms, vs. 3.0% (5/167) receiving HDR alone (p ≤ 0.01). Conclusions: We have observed no difference in PSA DFS in patients undergoing HDR vs. HDR + IMRT. Complications were similar, though RTOG Grade 1 and 2 late toxicity was higher in patients receiving HDR + IMRT. By omitting IMRT, rectal complications may be reduced. No significant financial relationships to disclose.
Published Version
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