February 5, 2008, 11:07 am
No Answers for Men With Prostate Cancer
Last year, 218,000 men were diagnosed with prostate cancer, but nobody can tell them what type of treatment is most likely to save their life.
Those are the findings of a troubling new report from the Agency for Healthcare Research and Quality, which analyzed hundreds of studies in an effort to advise men about the best treatments for prostate cancer. The report compared the effectiveness and risks of eight prostate cancer treatments, ranging from prostate removal to radioactive implants to no treatment at all. None of the studies provided definitive answers. Surprisingly, no single treatment emerged as superior to doing nothing at all.
“When it comes to prostate cancer, we have much to learn about which treatments work best,'’ said agency director Carolyn M. Clancy. “Patients should be informed about the benefits and harms of treatment options.”
But the study, published online in the Annals of Internal Medicine, gives men very little guidance. Prostate cancer is typically a slow-growing cancer, and many men can live with it for years, often dying of another cause. But some men have aggressive prostate cancers, and last year 27,050 men died from the disease. The lifetime risk of being diagnosed with prostate cancer has nearly doubled to 20 percent since the late 1980s, due mostly to expanded use of the prostate-specific antigen, or P.S.A., blood test. But the risk of dying of prostate cancer remains about 3 percent. “Considerable overdetection and overtreatment may exist,'’ an agency press release stated.
The agency review is based on analysis of 592 published articles of various treatment strategies. The studies looked at treatments that use rapid freezing and thawing (cryotherapy); minimally invasive surgery (laparoscopic or robotic-assisted radical prostatectomy); testicle removal or hormone therapy (androgen deprivation therapy); and high-intensity ultrasound or radiation therapy. The study also evaluated research on “watchful waiting,'’ which means monitoring the cancer and initiating treatment only if it appears the disease is progressing.
No one treatment emerged as the best option for prolonging life. And it was impossible to determine whether one treatment had fewer or less severe side effects.
Many of the treatments now in widespread use have never been evaluated in randomized controlled trials. In the research that is available, the characteristics of the men studied varied widely. And investigators used different definitions and methods, making reliable comparisons across studies impossible.
“Investigators’ definitions of adverse events and criteria to define event severity varied widely,'’ the report notes. “We could not derive precise estimates of specific adverse events for each treatment.'’
The report findings highlighted by the agency include:
All active treatments cause health problems, primarily urinary incontinence, bowel problems and erectile dysfunction. The chances of bowel problems or sexual dysfunction are similar for surgery and external radiation. Leaking of urine is at least six times more likely among surgery patients than those treated by external radiation.
Urinary leakage that occurs daily or more often was more common in men undergoing radical prostatectomy (35 percent) than external-beam radiation therapy (12 percent) or androgen deprivation (11 percent). Those were the findings of the 2003 Prostate Cancer Outcomes Study, a large, nationally representative survey of men with early prostate cancer.
External-beam radiation therapy and androgen deprivation were each associated with a higher frequency of bowel urgency (3 percent) compared with radical prostatectomy (1 percent), according to the 2003 report.
Inability to attain an erection was higher in men undergoing active intervention, especially androgen deprivation (86 percent) or radical prostatectomy (58 percent) than in men receiving watchful waiting (33 percent), according to the 2003 report.
One study showed that men who choose surgery over watchful waiting are less likely to die or have their cancer spread, but another study found no difference in survival between surgery and watchful waiting. The benefit, if any, appears to be limited to men under 65. However, few patients in the study had cancer detected through P.S.A. tests. As a result, it’s not clear if the results are applicable to the majority of men diagnosed with the disease.
Adding hormone therapy prior to prostate removal does not improve survival or decrease recurrence rates, but it does increase the chance of adverse events.
Combining radiation with hormone therapy may decrease mortality. But compared with radiation treatment alone, the combination increases the chances of impotence and abnormal breast development.
The most obvious trend identified in the complicated report is how little quality research exists for prostate cancer, despite the fact that it is the most diagnosed cancer in the country.
Studies comparing brachytherapy, radical prostatectomy, external-beam radiation therapy or cryotherapy were discontinued because of poor recruitment. Two ongoing trials, one in the United States and one in Britain, are evaluating surgery and radiation treatments compared with watchful waiting in men with early cancer. Other studies in progress or development include cryotherapy versus external-beam radiation and a trial evaluating radical prostatectomy versus watchful waiting.
“Successful completion of these studies is needed to provide accurate assessment of the comparative effectiveness and harms of therapies for localized prostate cancers,” the study authors said.
沒有留言:
張貼留言