New options for treating erectile dysfunction

Penile rehabilitation after treatment for prostate cancer

Studies indicate that anywhere from 30% to 70% of men who undergo radical prostatectomy or external beam radiation therapy, and 30% to 50% of men who opt for brachytherapy, will develop impotence after treatment. Recent insights into why this happens have led to a whole new approach in treating men who are interested in preserving their sexual function. The new therapies are often referred to collectively as penile rehabilitation, a concept first introduced by European physicians in 1997. Since then, penile rehabilitation has gradually evolved and is now being offered at a number of major teaching hospitals; it is less likely to be offered in the community setting. Although exact regimens vary, penile rehabilitation typically consists of oral or injected medications, alone or in combination with other interventions, to restore and preserve erectile function before any long-term damage occurs.

But this therapy remains controversial. Although preliminary results look promising, only a handful of reliable studies evaluating various types of penile rehabilitation have been published — and these have used different types of interventions, for different periods, so it is difficult to compare one method with another. Moreover, no consensus yet exists about which approach is best for a particular patient. Even so, penile rehabilitation may be something worth asking your doctor about if you have just been diagnosed with prostate cancer or are currently undergoing treatment. This article briefly reviews options in penile rehabilitation and the limited scientific evidence.

New insights into erectile dysfunction

When erectile function becomes impaired following radical prostatectomy, the problem has traditionally been attributed to nerve damage. The nerves that trigger erections may become damaged during surgery (even during so-called nerve-sparing surgery), leading to a problem known as neuropraxia — a temporary loss of function that theoretically should recover in time. The problem is that it can take as long as two years for the nerves to recover sufficiently to enable a man to have a spontaneous erection, and by then other damage may have occurred.

Recent research suggests that when the penis is flaccid for long periods of time, and therefore deprived of a lot of oxygen-rich blood, the low oxygen level causes some muscle cells in the columns of erectile tissue (corpora cavernosa) to lose their flexibility and gradually change into something akin to scar tissue. This scar tissue, moreover, seems to interfere with the penis’s ability to expand when it’s filled with blood. In fact, imaging studies indicate that blood may drain away from the penis rather than fill it.

Less research has been done about impotence after radiation therapy, but it appears that the underlying cascade of damaging events is similar to what occurs after radical prostatectomy. Radiation damages the lining of the small blood vessels, but this damage may take months or even years to manifest itself.

What all this means is that the traditional advice given to men — essentially to wait for erectile function to return on its own — may not be adequate. Simply put, erections seem to work on a use-it-or-lose-it basis. To prevent the secondary damage that may occur if the penis remains flaccid for a prolonged period, researchers now think that a better approach is to intervene soon after treatment to restore erectile function. (For more information about the studies highlighted here, see “For more information: Penile rehabilitation,” below.)

Options after radical prostatectomy

Preliminary studies indicate that penile rehabilitation for men who undergo radical prostatectomy is most effective when it begins soon after surgery and involves a combination of therapies.

A study published in 2005 in the Journal of Sexual Medicine, for example, reported the results of 132 men who were followed for 18 months after radical prostatectomy. A total of 58 men enrolled in a penile rehabilitation program within six months of surgery and took sildenafil (Viagra) or penile injections (see Figure 1) to achieve erections three times a week. When investigators followed up 18 months later, 52% of the men in the penile rehabilitation group said they could have spontaneous erections firm enough for intercourse, compared with 19% of the men who did not seek intervention. A larger proportion of men who underwent penile rehabilitation also said they responded to sildenafil when they needed to take it: 64% of the rehabilitation group responded versus 24% of the untreated group.

Although the study was not randomized — and thus its results could be influenced by patient self-selection or investigator bias — it confirmed the results of an earlier small study conducted by the European team that first pioneered the concept of penile rehabilitation. In 1997, researchers from Italy reported in the Journal of Urology that they had followed 30 men who underwent nerve-sparing radical prostatectomy, who were then randomized either to an observation group or to one that received penile injections three times a week, starting within a month after surgery. When investigators assessed the men at a six-month follow-up exam, they found that 67% of those who completed the entire schedule of injections reported spontaneous erections firm enough for intercourse, compared with 20% of men who did not receive injections. Imaging studies with ultrasound also indicated that the men who did not receive penile therapy had developed nerve, tissue, and vascular damage that may have contributed to their higher rates of erectile dysfunction.

Although both studies were small, they provide evidence that early intervention to restore erectile function may be important. Exactly when treatment should begin, though, is still an open question. One small study has looked at various intervention points. As reported in the Journal of Urology in 2003, investigators enrolled 73 men who underwent radical prostatectomy and randomly assigned them to receive injections at various times (within a month, 2–3 months, 4–6 months, or 7–12 months) after surgery. A total of 36 men received injections within the first three months, while 37 received injections between months 4 and 12. When the men were examined 5, 10, and 20 minutes after receiving the injection, the investigators found that 70% of the men who received an injection within the first three months after surgery could achieve erections firm enough for intercourse, compared with 40% of men receiving an injection after three months.

The results of this study are sometimes used to support the opinion that penile rehabilitation is most effective for men following radical prostatectomy if it begins within three months of surgery. However, it’s important to point out that the study involved only a single injection given within particular time frames after surgery; it’s not clear that the men would continue to respond so dramatically later on.

In addition to looking at the timing of treatment, investigators are conducting studies to determine the best mode of treatment. So far, the results indicate that a combination of therapies is probably best. For example, in 2005, investigators reported in Urology that men who had undergone radical prostatectomy and were not able to obtain erectile function after trying a vacuum constriction device (see Figure 2) might benefit by taking sildenafil before using the device. The study involved 31 men who began taking 100 mg of sildenafil an hour or two before using the vacuum device. At an 18-month follow-up, researchers found that seven men did not benefit from treatment, but 24 said that by using this combination therapy, they were able to have erections again.

Options after radiation therapy

The use of penile rehabilitation after radiation therapy has been less frequently studied, but one report in the Journal of Urology bears mention. In this study, 110 men who had developed erectile dysfunction after undergoing some form of radiation therapy were followed after they began taking sildenafil, at an average of eight months following cancer treatment. Investigators then checked in with them at three different times.

The investigators found that men who underwent brachytherapy had better results than those who underwent external beam radiation therapy. In the first year of penile rehabilitation treatment, 76% of men who underwent brachytherapy responded to sildenafil, and 60% reported erections firm enough for intercourse, compared with a 68% response rate among men who underwent external beam radiation therapy, with 50% reporting erections firm enough for intercourse. By the third year of treatment, however, response rates had fallen in both groups: Only 44% of the men who received brachytherapy were still responding to sildenafil, compared with 38% of men who received external beam radiation therapy. Likewise, only 26% of the men who received brachytherapy reported erections firm enough for intercourse, compared with 19% of those who received external beam radiation therapy.

What you can do now

Research continues in an effort to find new modalities for restoring erectile function following prostate cancer treatment. Some investigators are experimenting with ways to encourage nerves to regenerate faster, for example.

In the meantime, although the evidence isn’t perfect, you may want to ask your doctor about options for penile rehabilitation while you are discussing treatments. Although the field is still in its infancy, penile rehabilitation may help increase the odds that you will regain erectile function.

Originally published April 1, 2007; last reviewed April 22, 2011.