Predicting erectile dysfunction from prostate cancer treatment
Researchers have identified 12 DNA sequences that may help doctors determine which men will suffer from erectile dysfunction (ED) following radiation therapy for prostate cancer. Identifying these patients in advance of treatment may better inform men and their families as to which prostate cancer treatments are best for their specific cancer and lifestyle, according to a study to be published online September 27, 2012, in advance of the October 1, 2012 print issue, in the International Journal of Radiation Oncology.Biology.Physics (Red Journal), the official scientific journal of the American Society for Radiation Oncology (ASTRO). The findings could also guide doctors in recommending the most effective treatments that carry the least risk of patients developing ED.
The main treatments for prostate cancer - surgery, brachytherapy (seed implants) and external beam radiation therapy - are all very effective at curing prostate cancer. Unfortunately, each treatment places patients at risk for ED. Although many men will maintain their potency, doctors would like to identify which men are at greatest risk for the development of difficulty with sexual function.
In this multi-institutional, multi-national study, researchers from New York’s Mount Sinai School of Medicine, Albert Einstein College of Medicine of Yeshiva University in Bronx, N.Y., New York University School of Medicine, Florida Radiation Oncology Group in Jacksonville, Fla., and Maastricht University Medical Center in Maastricht, the Netherlands, examined 593 men who were treated with brachytherapy and/or external beam radiation therapy and hormone therapy. Of them, 260 reported erectile dysfunction.
“Through a two-stage genome-wide association study, 12 single nucleotide polymorphisms (SNPs) were identified that were associated with the development of erectile dysfunction after radiation treatment for prostate cancer,” said Barry S. Rosenstein, PhD, department of radiation oncology at New York’s Mount Sinai Medical School. “If validated further, these SNPs could provide the basis for a blood test that would enable radiation oncologists to predict more accurately which men are most likely to develop erectile dysfunction after prostate cancer radiation therapy.”
“Prostate cancer screening and treatment are undergoing major shifts,” said Harry Ostrer, MD, professor of pathology and genetics at Albert Einstein College of Medicine, director of genetic and genomic testing at Montefiore Medical Center and co-principal investigator of the study. “This is part of our ongoing effort to personalize and optimize treatment for prostate cancer.”
Erectile dysfunction, also called impotence, is the inability to develop or sustain an erection satisfactory for sexual intercourse.
Though prostate cancer is not a cause of erectile dysfunction, treatments for the disease can cause the problem. Among them:
- Surgery to remove the entire prostate gland
- Radiation therapy, whether by external beam or radioactive seed implants
- Hormone therapy
Different treatments can lead to impotence sooner than others.
When Can Erectile Dysfunction Occur After Treatment?
Surgery. Some degree of erectile dysfunction occurs right after surgery to remove the prostate, regardless of whether the technique is performed that tries to spare the nerve that controls erections.
The severity of the erectile dysfunction depends on the type of surgery, stage of cancer, and skill of the surgeon.
If the nerve-sparing technique is used, recovery from erectile dysfunction may occur within the first year following the procedure. Recovery of erectile function after a non-nerve-sparing surgery is unlikely, but possible.
One study shows erectile dysfunction rates of 66% for nerve-sparing prostatectomy versus 75% for non-nerve sparing surgery at one year after the surgery. The use of vacuum devices or erectile dysfunction drugs after the body has healed from surgery may improve the quality of erections and speed the return of normal sexual function.
If an erection can be achieved after surgery, one does not lose the ability to have an orgasm. However, they may be “dry” orgasms in which little (if any) ejaculate is produced. This results in infertility for most men, although most men are older when they are diagnosed for prostate cancer and may not be concerned. If desired, you could talk to your doctor about “banking” sperm before the procedure.
Radiation therapy. The onset of erectile dysfunction following radiation therapy is gradual and usually begins about six months following the treatment.
Erectile dysfunction is the most common long-term complication of radiation therapy. However, its occurrence decreases when more sophisticated treatments are used, such as radioactive seed implants (brachytherapy), intensity-modulated radiotherapy (IMRT), or 3-D conformal radiotherapy.
Hormone therapy. When hormone therapy is used, erectile dysfunction and decreased sexual desire may result approximately two to four weeks after the start of therapy. This is due to the testosterone-reducing action of the drugs