What’s worse than being rendered impotent and incontinent by prostate cancer treatment? Being rendered impotent and incontinent by prostate cancer treatment that was unnecessary.
Two large, well-conducted studies revealed what doctors have suspected for quite some time. Screening for prostate cancer using the PSA (prostate specific antigen) blood test does not save lives. In fact, PSA screening for prostate cancer does more harm, including impotence and incontinence, than good. Due to their importance, both studies were released online today by the New England Journal of Medicine, in advance of their publication next week.
According to the study, Mortality Results from a Randomized Prostate-Cancer Screening Trial:
From 1993 through 2001, we randomly assigned 76,693men at 10 U.S. study centers to receive either annual screening(38,343 subjects) or usual care as the control (38,350 subjects).Men in the screening group were offered annual PSA testing for6 years and digital rectal examination for 4 years. The subjectsand health care providers received the results and decided onthe type of follow-up evaluation. Usual care sometimes includedscreening, as some organizations have recommended. The numbersof all cancers and deaths and causes of death were ascertained…
Results … After 7 yearsof follow-up, the incidence of prostate cancer per 10,000 person-yearswas 116 (2820 cancers) in the screening group and 95 (2322 cancers)in the control group. The incidence of death per 10,000 person-yearswas 2.0 (50 deaths) in the screening group and 1.7 (44 deaths)in the control group …
Conclusions After 7 to 10 years of follow-up, the rate of deathfrom prostate cancer was very low and did not differ significantlybetween the two study groups.
The two graphs below present the results of the study. The graph on the left represents cases of prostate cancer and demonstrates that PSA screening was much more effective in diagnosing prostate cancer than examination alone. The graph on the right represents deaths from prostate cancer. Despite a significant increase in diagnosis of prostate cancer in the PSA group, there was minimal if any reduction in deaths from prostate cancer.
While deaths from prostate cancer were not decreased by PSA screening, serious side effects were dramatically increased.
Risks incurred from a screening process can result from thescreening itself or from downstream diagnostic or treatmentinterventions. In the screening group, the complications associatedwith screening were mild and infrequent… Medical complications from the diagnostic processoccurred in 68 of 10,000 diagnostic evaluations after positiveresults on screening. These complications were primarily infection,bleeding, clot formation, and urinary difficulties. Treatment-relatedcomplications, which are generally more serious, include infection,incontinence, impotence, and other disorders…
Why did the PSA screening test fail to save lives? The PSA screening test did diagnose more cancers than routine examination, so the test definitely works. The apparently paradoxical outcome is due to the nature of prostate cancer itself.
Most men will develop prostate cancer if they live long enough. However, most prostate cancers are very slow growing and usually do not kill the patient. A man with prostate cancer generally dies of some other cause long before the prostate cancer becomes life threatening. Therefore, the PSA test diagnoses many cases of prostate cancer that do not need to be treated as well as a few cases of prostate cancer that are very aggressive. Not only is there no benefit to diagnosing the slow growing prostate cancers, but there seems to be very little benefit to diagnosing the aggressive cancers early, since some do not respond to treatment even when administered in the early stages.
The second study, Screening and Prostate-Cancer Mortality in a Randomized European Study, showed a very small decrease in deaths associated with PSA screening. That decrease came at a very high price:
To prevent one prostate-cancerdeath, 1410 men (or 1068 men who actually underwent screening)would have to be screened, and an additional 48 men would haveto be treated.
For every death prevented, 1068 men had unnecessary biopsies, and 48 men had unnecessary treatment. That’s a problem, and it is made far more serious by the life altering side effects of treatment, impotence and incontinence.
Taken together, both studies provide convincing evidence that PSA screening for prostate cancer should be stopped. Too many men are seriously harmed, and very few if any men derive any benefit. The take home message for patients: Don’t get PSA screening for prostate cancer.