Sildenafil Citrate Improves Overall Sexual Function of Prostate Cancer Patients Receiving Radiation Therapy

BOSTON, Oct. 29, 2012 (GLOBE NEWSWIRE) -- Sildenafil citrate (SC), a phosphodiesterase type 5 inhibitor, administered before, during and after radiation therapy improved overall sexual function of prostate cancer patients, according to research presented today at the American Society for Radiation Oncology's (ASTRO's) 54th Annual Meeting.

This is the first prospective, randomized, double-blind, placebo controlled trial to determine if daily, adjuvant use of SC before, during and after radiation therapy preserves erectile function in prostate cancer patients. The study included 290 patients with clinically localized prostate cancer who were treated with external beam radiation therapy and/or permanent interstitial implantation and were randomly assigned to two groups (2:1 randomization): those who received a 50 mg dose daily of SC and those who received a placebo.

Patients in both groups were asked to complete the international index of erectile function (IIEF) and international prostate symptom score
(IPSS) questionnaires before therapy and at six, 12 and 24 months after radiation treatment. Results from 144 patients, those who completed the surveys before therapy and at least one additional time period, indicate that those in the SC group experienced improved overall sexual function compared to the placebo group at all time points, accounting for IIEF scores of 58.6 vs. 49.4, 56.3 vs. 48.2 and 54.9 vs. 47.6, respectively. Patient characteristics including age, use of brachytherapy, androgen deprivation therapy and baseline IIEFscores were similar in both treatment groups.

Patients received medication three days before their radiation treatment and continued with a daily dose for six months, after which daily use of SC or the placebo was discontinued and taken on an as-needed basis only. IIEF scores were based on patient feedback about their erectile function, orgasmic function, sexual desire, intercourse satisfaction and overall satisfaction.

"Our study found that prostate cancer patients treated with sildenafil citrate and adjuvant radiation treatment had improved overall erectile function and overall satisfaction of their sexual activity and function," said Michael J. Zelefsky, MD, lead author of the study and a radiation oncologist at Memorial Sloan-Kettering Cancer Center in New York. "The most significant improvements were seen at six and 12 months following treatment, with a slight dip at the 24-month mark, suggesting that future trials need to be conducted to demonstrate if a longer treatment duration can further improve patient outcomes."

The abstract, "Results of a Prospective Randomized Double-blind Placebo Controlled Trial Evaluating the Use Prophylactic Sildenafil Citrate During Radiation Therapy in the Treatment of Prostate Cancer," will be presented in detail during a scientific session at ASTRO's 54th Annual Meeting at 2:30 p.m. Eastern time on Monday, October 29, 2012. To speak with Dr. Zelefsky, call Michelle Kirkwood on October 28 -- 31, 2012, in the ASTRO Press Office at the Boston Convention and Exhibition Center at 617-954-3461 or 617-954-3462, or email michellek@astro.org.

ASTRO's 54th Annual Meeting, held in Boston, October 28 -- 31, 2012, is the premier scientific meeting in radiation oncology and brings together more than 11,000 attendees including oncologists from all disciplines, medical physicists, dosimetrists, radiation therapists, radiation oncology nurses and nurse practitioners, biologists, physician assistants, practice administrators, industry representatives and other health care professionals from around the world. The theme of the 2012 Annual Meeting is "Advancing Patient Care through Innovation"
and examines how innovation in technology and patient care delivery can lead to improved patient outcomes. The four-day scientific meeting includes six plenary papers and 410 oral presentations in 63 oral scientific sessions, and 1,724 posters and 130 digital posters in 18 tracks/topic areas.

ABOUT ASTRO

ASTRO is the largest radiation oncology society in the world, with more than 10,000 members who specialize in treating patients with radiation therapies. As the leading organization in radiation oncology, biology and physics, the Society is dedicated to improving patient care through education, clinical practice, advancement of science and advocacy. For more information on radiation therapy, visit www.rtanswers.org. To learn more about ASTRO, visit www.astro.org.

2012 American Society for Radiation Oncology (ASTRO) 54th Annual Meeting

News Briefing, Monday, October 29, 2012, 11:00 a.m., Eastern time

Scientific Session: Monday, October 29, 2012, 2:30 p.m. -- 3:45 p.m.
ET, Boston Convention & Exhibition Center

4 Results of a Prospective Randomized Double-blind Placebo Controlled Trial Evaluating the Use Prophylactic Sildenafil Citrate During Radiation Therapy in the Treatment of Prostate Cancer

M. J. Zelefsky1, D. Shasha2, M. Kollmeier1, R. E. Baser1, B. Cox1, R.
Stock3, R. D. Ennis2, N. Bar-Chama3, X. Pei1, J. Mulhall1, 1Memorial Sloan-Kettering Cancer Center, New York, NY, 2Beth Israel Medical Center, New York, NY, 3Mt Sinai Medical Center, New York, NY

Purpose/Objective(s): The concept of penile rehabilitation after prostate cancer therapy revolves around preservation of corpus cavernosal endothelial and smooth muscle integrity. A randomized, placebo controlled trial (RPCT) supports the PDE5 inhibitor sildenafil citrate (SC) as a rehabilitation strategy in men after radical prostatectomy. This study was undertaken to determine if the use adjuvant daily SC during and after radiotherapy for prostate cancer improves erectile function preservation.

Materials/Methods: 290 patients with clinically localized prostate cancer treated with external beam radiotherapy and or permanent interstitial implantation were enrolled in a randomized prospective trial comparing daily SC (50 mg) to placebo (2:1 randomization).
Medication/placebo was initiated 3 days before treatment and continued daily for 6 months, after which the drug therapy was discontinued and taken on an as-needed basis. Patients completed the international index of erectile function (IIEF) and international prostate symptom score
(IPSS) questionnaires pre-therapy and at 6, 12 and 24 months post-treatment. Current analysis is limited to patients who have completed questionnaires at pre-therapy plus at least one post-treatment time-point and who did not receive hormone therapy (n=144). All IIEF domains were scored including: erectile function (EF), orgasmic function (OF), sexual desire (SD), intercourse satisfaction (IS) and overall satisfaction (OS). Patient characteristics including age, use of brachytherapy, androgen deprivation therapy and baseline IIEF scores were balanced between the treatment groups.

Results: The IIEF overall scores were significantly higher in the SC arm compared to placebo at 6 months (p=0.006), 12 months (p=0.02) and
24 months (p=0.04) after therapy.

Conclusions: Daily SC administered during and after radiotherapy for prostate cancer resulted in improved overall sexual function compared to placebo at all time points. This is the first randomized prospective controlled-trial to demonstrate the utility of a PDE5 inhibitor as a rehabilitation strategy in the prostate cancer radiation therapy patient population.

Author Disclosure Block:

M.J. Zelefsky: A restricted educational grant from Pfizer, which was used to support research assistance to participating institutions for the current study. D. Shasha: None. M. Kollmeier: None. R.E. Baser:
None. B. Cox: None. R. Stock: None. R.D. Ennis: None. N. Bar-Chama:
None. X. Pei: None. J. Mulhall: Received a grant from Pfizer for a study on penile rehabilitation after radical prostatectomy. *Pfizer provided sildenafil citrate and placebo for the study.


CONTACT: Michelle Kirkwood, 703-286-1600, michellek@astro.org

 

Posted: October 2012

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