What is Radiation Therapy?
Radiation therapy involves exposing the prostate and, depending on the type of radiation used, also the surrounding areas to x-rays or other types of radiation designed to destroy cancer cells or at least prevent them from growing and spreading. The three types of radiation therapy used to treat prostate cancer are external beam radiation therapy (EBRT) and an associated EBRT called conformal EBRT, brachytherapy, and proton therapy. Read more on radiation therapy for prostate cancer
What is ERBT?
External beam radiation therapy, or EBRT, involves exposing the prostate gland and surrounding tissues to radiation doses, given daily in separate individual treatments. When the cancer cells are exposed to radiation every day for a designated treatment period (typically five days a week for 6 to 7 weeks), there is a better chance of catching the cancer cells when they are most sensitive and also not allowing them to recover from radiation damage. Read more on ERBT for prostate cancer
What is Conformal EBRT?
A more precise type of EBRT is conformal EBRT, in which the radiation oncologist uses CT images to help him or her better see where to treat the prostate gland. The three-dimensional images also allow the radiation oncologist to identify surrounding structures, such as the bladder and rectum, and to deliver a higher amount of radiation to the prostate while minimizing the radiation to surrounding normal tissue. Read more on EBRT for prostate cancer
What is Brachytherapy?
Brachytherapy involves implanting either permanent, tiny, radioactive capsules (“seeds”) or temporary needles into the cancerous prostate gland. The seeds send out a radioactive agent—either palladium 103 or iodine 125–over weeks or months to kill the tumor. Read more on brachytherapy for prostate cancer
What is Proton Therapy?
Proton therapy is a subtype of conformal radiation therapy that is more advanced than traditional radiation treatments. This approach offers prostate cancer patients a way to receive higher doses of conformal radiation, which radiation oncologists can achieve using advanced imaging techniques that allow them to identify the exact location of the tumor. Proton therapy is sometimes referred to as “bloodless surgery” because it treats the cancer with surgical precision that leaves nearby healthy tissues and organs nearly untouched. According to Dr. Jerry Slater, clinical director of Loma Linda’s Proton Therapy Center, proton therapy “allows very little scatter to the bladder and rectal areas, higher doses to the prostate, and significantly less side effects.” (National Association of Proton Therapy). Read more on proton therapy for prostate cancer
ED after Radiation Therapy
Erectile dysfunction is a common complication of radiation therapy for prostate cancer because the radiation always penetrates the erectile chambers. A difference between erectile dysfunction associated with radiation therapy and that which follows surgery, for example, is that it can take about six months before a man experiences erection problems. Fortunately, 50 to 60 percent of men regain erections with medication following radiation for prostate cancer. Recovery of erectile function tends to be better for men who undergo brachytherapy or conformal external beam radiation than traditional EBRT.
The development of erectile dysfunction following radiation depends on several factors, such as the man’s age, his erectile function before radiation, the type of radiation received, the dose of radiation, and overall health. These factors are important in relation to erectile dysfunction regardless of the type of radiation a man receives.
EBRT
Both types of EBRT can cause side effects that occur within 90 days after receiving radiation treatment (acute side effects) or more than 90 days after radiation treatment (late side effects). Erectile dysfunction is a late side effect because most cases develop about a year after treatment. In a review of 11 studies of the incidence of erectile dysfunction following EBRT, the findings varied widely. Erectile dysfunction was reported at a low of 37 percent of men three years after radiation in one study to a high of 76 percent after nearly 14 years in another study. (Mulhall p. 81) The broad range of incidence of erectile dysfunction is related to the many factors involved in determining if and/or when a man will regain erectile function following radiation. Read more on side effects of radiation therapy
Brachytherapy
As with EBRT, the percentage of men who experience erectile dysfunction following brachytherapy can vary greatly, since the incidence depends on the many factors already mentioned. In a review of seven studies of men who underwent brachytherapy, for example, the incidence of erectile dysfunction was 47 percent at five years in one study and 42 percent at 8 years in another.
The implanted seeds in brachytherapy are placed to hopefully avoid the nerves involved in erection. However, radiation damages or kills all cells in its pathway, regardless of whether they are healthy or cancer, and if nerves are close by, they may suffer some damage that could contribute to erectile dysfunction.
In a quality of life study, 614 men who received seed brachytherapy, EBRT, or radical prostatectomy were compared over a two year follow-up period. The researchers found that men who underwent low-dose (seed) brachytherapy had better erectile function than those who had either of the other two treatments for prostate cancer. (Ferrer) Two other studies report that 15 to 30 percent of men may experience erectile dysfunction following low-dose brachytherapy. (Pinkawa; Moule)
There is also some evidence that high-dose brachytherapy may further reduce the risk of erectile dysfunction compared with low-dose treatment. In one study of 65 men who received high-dose brachytherapy and 84 who received low-dose treatment, the rates of erectile dysfunction after three years was 45 percent in the low-dose group and 16 percent in the high-dose group. (Grills) In a more recent study, 248 men were treated with high-dose and 206 received low-dose brachytherapy. At five-year follow-up, the rate of erectile dysfunction was 30 percent in the low-dose group and 20 percent in the high-dose group. (Martinez)
Proton Therapy
Although little research has been published on the side effects of proton radiation therapy, a recent study published in the Journal of the American Medical Association offers some insight. Researchers evaluated 280 men who had been treated with either conventional or high-dose combined photon and proton radiation for early prostate cancer. At a median of 9.4 years after treatment, patient-reported erectile dysfunction was 68.2% vs. 65.9 %. (Talcott)
See also
Questions to Ask About Radiation Therapy
References
Ferrer M et al. Health-related quality of life 2 years after treatment with radical prostatectomy, prostate brachytherapy, or external beam radiotherapy in patients with clinically localized prostate cancer. Int J Radiat Oncol Biol Phys 2008; 72(2): 421-32
Grills IS et al. High dose rate brachytherapy as prostate cancer monotherapy reduces toxicity compared to low dose rate palladium seeds. J Urol 2004; 171(3): 1098-104
Martinez AA et al. High-dose rate prostate brachytherapy: an excellent accelerated-hypofractionated treatment for favorable prostate cancer. Am J Clin Oncol 2010 Oct; 33(5): 481-88
Moule RN, Hoskin PJ. Non-surgical treatment of localized prostate cancer. Surg Oncol 2009; 18(3): 255-67
National Association of Proton Therapy: http://www.proton-therapy.org/
Pinkawa M et al. Health-related quality of life after permanent I-125 brachytherapy and conformal external beam radiotherapy for prostate cancer—a matched-pair comparison. Radiother Oncol 2009 May; 91(2): 225-31
Talcott JA et al. Patient-reported long-term outcomes after conventional and high-dose combined proton and photon radiation for early prostate cancer. JAMA 2010 Mar 17; 303(11): 1046-53
