High-dose-rate brachytherapy for large prostate volumes (>= 50 cc)-Uncompromised dosimetric coverage and acceptable toxicity

PURPOSE: The purpose of this study was to review our single-institution experience using highdose-rate (HDR) brachytherapy in patients with large-volurne prostate glands (>= 50 cc). METHODS AND MATERIALS: Fifty-four patients treated with HDR brachytherapy for prostate cancer at the Penrose Cancer Center between 2001 and 2006 were identified as having an ultrasound volume of at least 50 cc at the time of implant (range, 50-97.3 cc; mean, 61.5 cc; median, 57 cc; upper quartile, 83.3-97.3 cc). Neoadjuvant hormones (17 patients) were not routinely recominended unless the initial ultrasound volume suggested pubic arch interference or the patient's Gleason score or prostate specific antigen prompted use. All patients received HDR brachytherapy as a boost before or after conformal external beam radiation therapy to 4500 cGy. Boost brachytherapy doses ranged from 1600 to 1900 cGy, given in two to three fractions. RESULTS: The median D-90 (minimal dose to 90% of the prostate) was 109% of prescription dose (range, 95-115%) and the median V-100 (volume receiving 100% of the dose) was 96% (range, 90-99%). V-150 ranged from 10% to 35%, with a median value of 18.3%. Six patients (11%) required temporary placement of a urinary catheter for acute obstructive symptoms after brachytherapy. With a median followup of 1.8 years, there has been a single case of Grade 2 gastrointesfinal toxicity and I patient has developed a bulbo-urethral stricture requiring dilation. There have been no cases of rectal bleeding. CONCLUSIONS: Large prostate volume is not a contraindication to HDR brachytherapy. Excellent dosimetric coverage can be attained with acceptable acute toxicity. (D 2008 American Brachytherapy Society. All rights reserved.