Specifically, at 5 years, 64% of men in the external beam group and 63% in the combination group were able to have erection sufficient for intercourse with aids, usually sildenafil (Viagra) or tadalafil (Cialis). But a much higher percentage – 79% and 92%, respectively – were able to be sexually active with aids.
“The difference between those outcomes by metric implies sexual activity apart from intercourse,” Dr. McLaughlin said. “The gap between sexual intercourse and sexual activity demonstrates the limitations of this scale, the International Index of Erectile Function, in this age-group.”
This finding lends support to the new concept of manopause, the male equivalent of menopause, he said. “For many couples, [with aging,] sexual intercourse becomes difficult or even painful, so they shift to other activities. My shorthand for that is 69 at 69, and I usually get a knowing chuckle when I say that to couples. But many couples will say, ‘Well, we still take care of each other even though it’s not sexual intercourse.’ ”
The vessel-sparing radiation therapy also was associated with very high cure rates: 98% for low-risk prostate cancer, 96% for intermediate-risk prostate cancer, and 87% for high-risk prostate cancer.
“Typically, intensive treatments will cause quite a decrement in quality of life,” Dr. McLaughlin noted. “So to have this kind of ‘have your cake and eat it too’ result, of cure and quality of life, I think is very hopeful for men.”
In multivariate analysis, neither radiation therapy group nor any dose parameters predicted sexual outcomes. However, when analyses incorporated data from 44 men treated off protocol who also received hormone therapy, considered to be a major confounder, that therapy was indeed associated with poorer sexual function.
The vessel-sparing technique is probably not ready for routine use, according to Dr. McLaughlin. “I think it’s not the standard and I can’t say it should be the standard based on our study yet, even those these are spectacular sexual function preservation results.”
He and his colleagues have developed an online teaching tool, called Prostadoodle, that shows radiation oncologists how to define these critical vessels if they want to do so. “You can actually do it without doing an MRI if you learn the anatomy, and you can definitely approximate it. But to do it the way we did it actually was what I would consider a research protocol – a lot of effort for each patient, hours and hours even for each patient. It just wasn’t a simple thing to reproduce. I think it’s going to be a while before we can say, ‘You must do this.’ But I do think these results are very promising,” he said.
“Depending on the anatomy and where the disease is, it could really make a difference as to whether you could vessel spare or not,” said Dr. Colleen Lawton, professor and vice chair and clinical director, department of radiation oncology, Medical College of Wisconsin, Milwaukee, and moderator of the press briefing. “If you’ve got disease low in the prostate, what we call the apex, which is close to all of these vessels, you don’t want to miss the disease. So it’s going to be a balancing act.”