The study, which is published in the New England Journal of Medicine, suggests that many men who undergo the surgery, which is called a radical prostatectomy, are being needlessly exposed to the risk of debilitating side effects, including erectile dysfunction and incontinence.
The prostate is a walnut-sized gland that wraps around the junction of the bladder and urethra, the tube that carries urine out of the body.
Radical prostatectomy, where a doctor removes the prostate and some of the tissue around it, can damage the nerves and blood vessels that control the bladder and penis, leading to impotence and urine leakage.
Indeed, 81% of men in the study who had surgery to remove their prostate had erectile dysfunction within two years of their procedures, nearly double the ED experienced by men assigned to observation. Roughly 17% of men in the surgery group experienced urinary incontinence, about three times the percentage in the observation group.
The men in this study had their cancer diagnosed by a prostate specific antigen test (PSA). There has been a lot of debate over the effectiveness of this test at showing appropriate risk. In this case, the research shows that two-thirds of the men with a PSA below 10 who had surgery did not appear to have a real benefit from that surgery. On the other hand, some doctors would say a PSA of 10, even if the cancer has not spread beyond the prostate, is too risky.
Not everyone agrees. "There are far more people treated than are at risk of death from prostate cancer," says Ian M. Thompson Jr., MD, director of the Cancer Therapy & Research Center at the University of Texas Health Science Center in San Antonio.
"You may have a low risk of a tumor itself, and a far higher risk of side effects. A death from prostate cancer is [obviously] a huge side effect, but it tends to be down the road. On the other hand, a treatment-related urinary, sexual, or bowel complication, in the case of radiation may be more acute and for a longer period of time," says Thompson, who wrote an editorial on the study but was not involved in the research.
Surgery Becoming More Common
Prostate cancer is the second most frequently diagnosed cancer in men, behind skin cancer. But most prostate cancers are slow growing, and many men with prostate cancer live relatively untroubled by their tumors and will die of other causes.
Despite the good odds of survival associated with most cases, studies show that radical prostatectomy procedures are becoming more common. A study published in June in the Journal of Urology, for example, found the number of radical prostatectomies roughly doubled in the U.S. between 2004 and 2010.
"The idea that we are overtreating prostate cancer has been well known for a long time. Many men with low-risk prostate cancer will probably die of other causes rather than die of prostate cancer," says Manish Vira, MD, director of the Fellowship Program in Urologic Oncology at the North Shore-LIJ Health System's Smith Institute for Urology in New Hyde Park, N.Y.
For that group, says Vira, who was not involved in the research, treatment will almost certainly do more harm than good.
But other independent experts think the study is limited in what it can say because it only followed most people for around a decade. Because prostate cancers grow so slowly, says Ballentine Carter, MD, director of adult urology at the Johns Hopkins School of Medicine, 10 years may not be enough time to see a difference.
"In the world of prostate cancer, 10 years is not very long follow-up, he says. Because over a 10-year period, men who are diagnosed with a disease that's potentially harmful aren't harmed in 10 years, and the study shows that because very few people in either group died of prostate cancer," he says.
But there were important differences between the two groups in the number of men who went on to develop cancer that spread to the bone, Carter says.
In the surgery group, 17 men had their cancer spread to their bone over the course of the study, compared with 39 in the observation group. Surgery appeared to reduce a man's risk of having his cancer spread by about 60% over observation alone.
The study followed 731 men with cancer than had not yet spread beyond the prostate. The average age of men in the study was 67.
About half the men were assigned to have radical prostatectomies; the other half were assigned to observation. All the men saw a doctor every six months. They had bone scans every five years to check for cancer spread to the bone.
"This really is the first large study to address the kind of men who are dealing with prostate cancer as it's being diagnosed in the United States these days," primarily through PSA tests, says researcher Michael J. Barry, MD, a clinical professor of medicine at Harvard Medical School.
Based on a combination of factors that included a man's PSA, the way the cancer looked under a microscope, and the size of the tumor, doctors assessed how risky the cancer appeared to be. Forty percent of men in the study had tumors that were considered low-risk; 34% were intermediate-risk; and 21% were considered high-risk.
After an average of 12 years, there was no significant difference in the number of overall deaths or deaths related to prostate cancer between the two groups -- 47% of men who had surgery died compared to 49.9% of men who didn't have surgery. Among men assigned to radical prostatectomy, 21 (5.8%) died from prostate cancer or treatment, compared with 31 men (8.4%) assigned to observation -- a difference so small that it might have been caused by chance alone.
Only men who had PSA levels higher than 10 and perhaps those with intermediate- or high-risk tumors appeared to gain any benefit from surgery.
"What was remarkable was that even with observation, the chance of dying of prostate cancer was quite low -- about seven chances in 100 over 12 years," Barry says. "People have always said that for these PSA-discovered cancers that you're much more likely to die with prostate cancer than of it, and I think we proved that's way more likely."
Advice to Patients
Thompson says that men who are diagnosed with prostate cancer are lucky in at least one respect: Because the cancer is typically slow-growing, they have plenty of time to make a careful decision about how to handle it.
"For most prostate cancers, you have the luxury of taking the time to make a very informed and very methodically processed determination," he says.
The first thing to consider is your age. One in six men will get prostate cancer at some point in their lives. Doctors rarely recommend treatment for those diagnosed over 75 years of age.
Other factors to consider are your family history and the aggressiveness of disease. A PSA over 10, and a Gleason score over 7, are some indicators of a more aggressive cancer. A Gleason score is based on how the cancer cells look under a microscope.
"Over a 10-year period, a person who doesn't have an aggressive prostate cancer is not going to benefit from an operation," Carter says.