A team led by Jeremy L. Millar, MBChB, of Monash University in Melbourne, Australia, conducted a prospective, longitudinal single-center study of 366 patients who underwent BT. All patients completed the International Index of Erectile Function 5-item questionnaire before treatment and at regular follow-up post-treatment. Of the 366 patients, 277 (76%) reported normal erectile function and 89 (24%) reported mild erectile dysfunction prior to treatment.
The patients were followed up for a median of 41 months. The 5-year actuarial rate of EF preservation was 59%, the investigators reported online ahead of print in Radiotherapy and Oncology.
The 5-year actuarial EF preservation rate was significantly higher in patients with a Gleason score below 7 than in those with a Gleason score of 7 (73% vs. 18%). The rate also was significantly higher among patients younger than 60 years than older patients (69% vs. 50%) and significantly lower in patients with than without medical comorbidities (47% vs. 64%). In addition, patients who received a biologically effective dose (BED) of radiation below 150 Gy had a significantly higher 5-year actuarial rate of EF preservation than those who had a BED of 150 Gy or greater (74% vs. 52%).
On multivariate analysis, Gleason score was the strongest predictor of EF preservation, with a score below 7 associated with a 3.7 increased likelihood of EF preservation compared with a Gleason score of 7. A BED below 150 Gy was associated with a 60% increased likelihood of EF preservation compared with a BED of 150 Gy or higher.
The study has 2 important take-home messages, Dr. Millar told Renal & Urology News. First, overall, the results are consistent with a large amount of previous work suggesting good rates of EF preservation with BT for PCa, said Dr. Millar, associate professor of surgery and public health.
Second, the follow-up in the current study was longer than in most previous studies of EF after PCa treatment, and the rates of long-term preservation of EF contrast with the widely-held belief that EF after BT rapidly and materially gets worse after 1 or 2 years, he said.