Matched-pair analysis of conformal high-dose-rate brachytherapy boost versus external-beam radiation therapy alone for locally advanced prostate cancer

Purpose: We performed a matched-pair analysis to compare our institution's experience in treating locally advanced prostate cancer with external-beam radiation therapy (EBRT) alone to EBRT in combination with conformal inters titial high-dose-rate (HDR) brachytherapy boosts (EBRT + HDR), Materials and Methods: From 1991 to 1998, 161 patients with locally advance d prostate cancer were prospectively treated with EBRT + HDR at William Bea umont Hospital, Royal Oak, Michigan. Patients with any of the following cha racteristics were eligible for study entry: pretreatment prostate-specific antigen (PSA) level of greater than or equal to 10.0 ng/mL, Gleason score g reater than or equal to 7, or clinical stage T2b to T3c, Pelvic EBRT (46.0 Gy) was supplemented with three (1991 through 1995) or two (1995 through 19 98) ultrasound-guided transperineal interstitial iridium-192 HDR implants, The brachytherapy dose was escalated from 5.50 to 10.50 Gy per implant, Each of the 161 EBRT + HDR patients wets randomly matched with a unique EBR T-alone patient. Patients were matched according to PSA level, Gleason scor e, T stage, and follow-up duration. The median PSA fallow-up was 2.5 years for both EBRT + HDR and EBRT alone. Results: EBRT + HDR patients demonstrated significantly lower PSA nadir lev els (median, 0.4 ng/mL) compared with those receiving EBRT alone (median, 1 .1 ng/mL), The 5-year biochemical control rater for EBRT + HDR versus EBRT- alone patients were 67% versus 44%, respectively (P < .001), On multivariat e analyses, pretreatment PSA, Gleason score, T stage, and the use of EBRT a lone were significantly associated with biochemical failure, Those patients in both treatment groups who experienced biochemical failure had a lower 5 -year cause-specific survival rate than patients who were biochemically con trolled (84% v 100%; P < .001). Conclusion: Locally advanced prostate cancer patients treated with EBRT + H DR demonstrate improved biochemical control compared with those who are tre ated with conventional doses of EBRT alone, J Clin Oncol 18:2869-2880, (C) 2000 by American Society of Clinical Oncology.