A single injection eases BPH-related symptoms for up to a year.
ANAHEIM, Calif.—Just one injection of botulinum toxin type A (Botox) into the prostate may provide relief from BPH-related lower urinary tract symptoms (LUTS) for up to 12 months.
The benefit appears to be related not to prostate volume changes but to an inhibitory effect on smooth muscle tone, researchers said. Findings suggest that inflammatory processes and aberrant sensory function may play a role in LUTS secondary to BPH, they noted.
“These injections relax the prostate,” said senior author Michael Chancellor, MD, professor of urology and gynecology at the University of Pittsburgh School of Medicine. “The injections even induce cellular death through apoptosis. We are also seeing PSA scores dropping.”
“Anything that can potentially lower the PSA … is of importance in our field, and we see about a 10%-15% decrease in PSA with prostate botulinum toxin injections,” added lead investigator Y.C. Chuang, assistant professor of urology at ChangGungMemorialHospital in Taiwan.
The researchers in Taiwan looked at 37 men (mean age 67.2 years) with an International Prostate Symptom Score (IPSS) of 8 or greater and a maximal flow rate (Qmax) less than 12 mL/sec. None of the patients had responded to medical management. The patients received botulinum toxin type A (Allergan Inc.) 100 units for prostates smaller than 30 mL (20 patients) or 200 units (17 patients) for prostates larger than 30 mL. The injections were administered transperineally under transrectal ultrasound guidance.
Dr. Chuang, who presented the findings here at the American Urological Association annual meeting, said exclusion criteria included confirmed or suspected malignancy, urinary retention, previous pelvic surgery or trauma, and previous invasive treatment for BPH. For this study, researchers evaluated prostate size, IPSS, quality of life (QOL), and Qmax pre-treatment and post-treatment.
The investigators observed no significant local or systemic adverse effects in any of the patients; 27 (73%) had a greater than 30% improvement on LUTS and QOL indices. Dr. Chancellor said he and his colleagues were “pleasantly surprised” to see that just one injection yielded benefits for months beyond what had been expected.
“When treating facial wrinkles, an injection lasts only three or four months,” Dr. Chancellor told Renal & Urology News. “In the prostate, one injection has sustained efficacy for 12 months.”
At six and 12 months post treatment, prostate volume had decreased by less than 15% in both the 100- and 200-unit groups. In addition, six patients in the 100-unit group and five in the 200-unit group did not have any significant change in prostate volume. Even though the prostate volume was not decreased, six of these 11 patients (54.5%) still had a greater than 30% improvement on Qmax, LUTS, and QOL measurements. Moreover, the percentage of prostate volume change did not correlate with percentage change of Qmax, LUTS, and QOL.
Placebo-controlled trials of botulinum toxin for BPH symptoms are underway. Researchers will examine histology and molecular biology to elucidate the mechanisms of action.