By Will Boggs MD
NEW YORK (Reuters Health) - Vessel-sparing radiotherapy preserved erectile function in most men with localized prostate cancer, in a phase II study.
"We would hope that physicians understand there is a new standard of successful treatment for prostate cancer - cure with quality of life,” Dr. Patrick W. McLaughlin from University of Michigan in Ann Arbor told Reuters Health by email. “In the past, men seeking cure would potentially have to lose function to accomplish cure, but this study suggests with additional attention to mapping of critical adjacent structures, both cure and quality of life can be accomplished in the majority of men diagnosed with prostate cancer.”
Dr. McLaughlin and colleagues developed vessel-sparing radiotherapy with the intention of delivering the prescribed radiotherapy dose to the prostate with maximal sparing of the bilateral corpus cavernosum and internal pudendal artery.
In their February 21st European Urology online report, they provide five-year patient-reported erectile function preservation rates and long-term tumor control outcomes in 144 men treated with vessel-sparing radiotherapy between 2001 and 2009.
Sixty-one percent received a combination of intensity-modulated radiotherapy with brachytherapy, and 33% also received androgen deprivation therapy.
At five years, 35% of men could be sexually active without the use of aids, and 53% reported that they were sexually active but required aids. Most of the sexual aids used were phosphodiesterase-type 5 inhibitors.
Two-thirds of men at five years reported moderate to very high confidence in the ability to achieve and keep an erection.
Overall, 13 of 135 men developed biochemical failure, which translated into biochemical relapse-free survival rates of 99.3% at five years and 89.9% at 10 years.
Based on previously validated models, this cohort would have an expected potency rate (able to achieve an erection firm enough for intercourse) of 42% at two years after standard external beam radiotherapy (EBRT) and 24% at two years after nerve-sparing radical prostatectomy, in contrast to the actual observed rate of 78% here.
Among men with erections firm enough for intercourse at baseline, two-year preservation of functional erections was 87% for vessel-sparing radiotherapy, 69% for conventional EBRT, and 42% for nerve-sparing medical prostatectomy.
Results did not differ consistently between patients receiving EBRT alone versus EBRT plus brachytherapy, but patients who received antigen deprivation therapy generally had worse erectile function outcomes at two years and had moderately recovered by 5 years.
“This proves that dose can be intensified to the prostate without affecting sexual outcomes,” Dr. McLaughlin said. “It validates what we term the functional anatomy approach - by defining critical adjacent functioning tissues visible on MRI and poorly visualized on CT we can include these structures in the treatment plan and drastically limit dose compared to CT based plans.”
“In any man diagnosed with prostate cancer with good baseline sexual function, vessel-sparing radiation therapy will have a role,” he said.
“Although this study emphasized defining and sparing critical adjacent structures related to sexual function, other critical functional domains, such as bladder and sphincter function and rectal and anal function, can all be mapped and spared through MRI-based planning,” Dr. McLaughlin said. “We will be reporting improved outcomes in these critical domains similar to improvements in sexual function outcomes.”
Dr. McLaughlin provided this link to a full video summary of the functional anatomy approach: http://bit.ly/2lXTdWG.
Eur Urol 2017.
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