Study: PSA Screening Caused 1 Million Unnecessary Prostate Cancer Diagnoses
By Denise Mann
MONDAY, August 31, 2009 (Health.com) — More than 1 million American men may have been unnecessarily diagnosed and treated for prostate cancer since widespread use of the prostate-specific antigen (PSA) blood test began in 1987, a new study says.
“All overdiagnosed patients are needlessly exposed to the hassle factors of obtaining treatment, the financial implications of the diagnosis, and the anxieties associated with becoming a cancer patient,” concluded the researchers, who were led by H. Gilbert Welch, MD, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice, in Hanover, N.H. The study was published online in the August 31 issue of the Journal of the National Cancer Institute.
The researchers acknowledge that prostate cancer screenings can indeed save lives; however, their study was conducted to highlight the majority of men who did not benefit from the test.
Screening benefits are questionable
PSA is a protein produced by cells of the prostate gland. The higher a man’s PSA level, the more likely it is that he has prostate cancer. However, there are other reasons for a high PSA level.
Also, PSA tests can detect small prostate cancers, including some very slow-growing tumors that are unlikely to be life-threatening and may not add any relevant information about aggressive prostate tumors that are already spreading.
For these reasons, PSA testing is considered controversial because it is not known whether the test actually saves lives or simply leads to unnecessary stress and potentially harmful treatment.
Two recent studies in the New England Journal of Medicine have added to the debate. European researchers found that PSA testing decreases prostate cancer death by 20%, but a U.S. study found no such effect.
For 1 life saved, more than 20 overdiagnosed
In the new study, the researchers examined age-specific prostate cancer incidence and treatment data to figure out the effect of PSA screening on the diagnosis and treatment of prostate cancer.
Overall, 1.3 million men were diagnosed with prostate cancer that wouldn’t have been discovered without the PSA initiative, and more than 1 million of these men were treated between 1986 and 2005.
Assuming that the decline in prostate cancer deaths over this time could be attributed to these screenings, the researchers estimated that for every one man who avoids a death, more than 20 men—and as many as 50—had to be overdiagnosed and treated needlessly.
“[Of those] maybe one-third will have treatment problems such as impotence or incontinence,” says Dr. Welch. Treatments for prostate cancer, including the surgical removal of the prostate gland, can result in such conditions, or even death.
Younger men are at greater risk
The increased diagnosis was most pronounced in younger men, the study showed. Since 1986, prostate cancer diagnoses among men in their 50s had tripled, and there had been a sevenfold increase in diagnoses in men in their 40s.
“I was surprised by how much growth there has been in younger men,” says Dr. Welch. “We are taking what was an old man’s disease and turning it into a young man’s disease. And some of the treatment side effects such as impotence and incontinence are even bigger problems when they start occurring in younger men.”
Differentiating slow- vs. fast-growing cancers
Christopher J. Logothetis, MD, a professor and chairman of the Department of Genitourinary Medical Oncology at the University of Texas M.D. Anderson Cancer Center, in Houston, agrees that doctors “are overdiagnosing and overtreating prostate cancer in the PSA screening era.”
The real issue is not the PSA test per se, but how best to apply its results, he says.
“We need to develop a strategy by which we take the good things from screening and protect from the bad things,” Dr. Logothetis says. “Don’t throw the baby out with the bathwater.”
If a PSA test result and a subsequent biopsy do indicate cancer, “we need to know if it is a cancer that possesses the potential to be lethal,” he says. Some prostate tumors are slow-growing and do not need treatment.
“Screening needs to be continued, but patients need to be informed that not all prostate cancers require an intervention,” Dr. Logothetis explains. “A high PSA doesn’t mean you have cancer, and if you do, it does not [necessarily] mean it needs treatment.”
Otis W. Brawley, MD, the chief medical officer at the American Cancer Society, echoed these thoughts in an editorial accompanying the study.
“We desperately need the ability to predict which patient has a localized cancer that is going to metastasize and cause suffering and death and which patient has a cancer that is destined to stay in the patient's prostate for the remainder of his life," he wrote.
As it stands, there is no clear consensus on prostate cancer screening from the major medical organizations.
The American Cancer Society does not support routine testing for prostate cancer. The group states that doctors and patients should weigh the potential benefits and risks. By contrast, the American Urological Association urges baseline PSA blood testing for all men starting at age 40.
“There is no correct answer,” says Dr. Welch. “You are not crazy to get screened and you are not crazy not to.”