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

Abstract 

Purpose

The purpose of this study was to review our single-institution experience using high-dose-rate (HDR) brachytherapy in patients with large-volume prostate glands (≥50cc).

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 50cc at the time of implant (range, 50–97.3cc; mean, 61.5cc; median, 57cc; upper quartile, 83.3–97.3cc). Neoadjuvant hormones (17 patients) were not routinely recommended 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 4500cGy. Boost brachytherapy doses ranged from 1600 to 1900cGy, given in two to three fractions.

Results

The median D₉₀ (minimal dose to 90% of the prostate) was 109% of prescription dose (range, 95–115%) and the median V₁₀₀ (volume receiving 100% of the dose) was 96% (range, 90–99%). V₁₅₀ 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 gastrointestinal toxicity and 1 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.

Keywords: Prostate, Large volume, High-dose-rate brachytherapy, Pubic arch interference