Prostate Cancer Test Leads to Overdiagnosis, Research Finds
Roughly one-third of men older than 65 who have been diagnosed with prostate cancer through the use of a commonly used test may be overdiagnosed and are receiving unnecessary treatments, according to a new study published today. The study, a statistical analysis of prostate cancer incidence conducted by the Fred Hutchinson Cancer Research Center in Seattle, found that 35% of patients screened with the Prostate Specific Antigen test would never experience any symptoms of the disease in their lifetimes.
The study’s findings address a long-running controversy over the PSA test, which measures a level of protein in the blood associated with the cancer. While the test can provide early detection of the disease, the treatments carry the risk of side effects such as impotence and incontinence.
The study, published in the Journal of the National Cancer Institute, combined data from a national registry of cancer cases and PSA screening information from Medicare records to create a statistical model of how many men were overdiagnosed.
Dr. Durado Brooks, director of the prostate and colorectal cancer national office at the American Cancer Society, stressed that the study shows that PSA screening allowed most cancers to be picked up earlier. But the study did not address the effectiveness of early diagnosis in decreasing the number of deaths the disease causes.
This question can only be answered with randomized clinical trials, which are being conducted in the U.S. and Europe. Results from the American trial, which is sponsored by the National Cancer Institute, are not expected for another four to six years.
Prostate cancer can range from a disease that is very aggressive to one that is relatively harmless. Many men can live out their life with prostate cancer without being diagnosed, said Brooks. But he added that it is “difficult to determine which cancers will be slow growers and which will be aggressive bad actors.”
Nearly 200,000 men will be diagnosed this year with prostate cancer, which is the second leading cause of cancer death in men, according to the American Cancer Society.
Treatment options include surgery, radiation, hormone therapy or no treatment. Each individual will have a different set of factors, such as PSA levels, age or other health conditions, that will determine what treatment to pursue, said Ruth Etzioni, lead author of the study and a biostatistician at the cancer research center.
Because of the side effects of treatment, some men may opt out of treatment and instead closely monitor their disease.
This “watchful waiting” approach may be appropriate for older men or men with other health problems, such as advanced heart disease or diabetes, Brooks said. If a patient is expected to live for only three to five years because of other health conditions, there may be no point in undergoing prostate cancer therapy, he said.
The American Cancer Society encourages men to be screened for prostate cancer or to discuss the issue with their doctor. Men with a family history of the disease should definitely be screened, the cancer society says.
