By William J. Catalona
Tuesday, August 26, 2008
Numerous media reports followed a federal task force's announcement this month that there is insufficient medical evidence to assess the risks and benefits of prostate cancer screening in men younger than 75 and that doctors should stop testing men over age 75 [" U.S. Panel Questions Prostate Screening; 'Dramatic' Risks for Older Men Cited," front page, Aug. 5].
It's important to note that consideration was not given to the overwhelming body of emerging evidence that screening with PSA tests and digital rectal exams saves lives. Rates of death from prostate cancer and rates of diagnosis at advanced stages have decreased markedly since testing became widespread.
As a physician and a researcher specializing in prostate cancer, I worry that this recommendation will result in delays in potentially lifesaving treatment and possibly the unnecessary loss of life.
The U.S. Preventive Services Task Force did not even recommend screening for men at higher risk because of race or family history. The task force reasoned that screening might harm more men than it helps and that in men over 75 there was moderate certainty that the harm outweighs the benefits.
Physicians and patients who are concerned about preventing prostate cancer deaths choose to screen with prostate-specific antigen (PSA) tests because an inconclusive but increasingly compelling body of evidence shows that the screening reduces suffering and death from prostate cancer -- the second-leading cause of cancer death among men in the United States.
Numerous studies have shown that PSA-based tests, such as those that detect increases in PSA over time and the percentage of PSA floating free in the blood, help to decrease unnecessary biopsies and also identify men with the most aggressive tumors so that they can receive timely treatment.
Eliminating screening also eliminates the possibility for early diagnosis and curative treatment in healthy men. Until we can prevent prostate cancer or cure patients at advanced stages of the disease, the only practical strategy for reducing death rates is early diagnosis and effective treatment. Because this tumor arises silently and often passes into an incurable stage before symptoms occur, the only way to detect it early is through screening.
Both the American Urological Association and the American Cancer Society recommend offering screening beginning at age 50 in men with a life expectancy of 10 years. High-risk men, such as African Americans and those with a strong family history of prostate cancer, are urged to consider screening at an earlier age. The National Comprehensive Cancer Network's guidelines recommend that screening begin at age 40. These guidelines include emerging evidence to help guide physicians and patients in their diagnostic and treatment decisions. These organizations, unlike the U.S. Preventive Services Task Force, have urologists on their panels who see firsthand the ravages of prostate cancer.
Consider that in the United States alone, the rate of advanced cancer at the time of diagnosis has fallen 75 percent since the PSA screening era began, and age-adjusted prostate cancer death rates have declined 35 percent. Statistical studies suggest that 45 to 70 percent of this decrease is due to PSA screening.
Evidence from U.S. cancer registries shows less advanced cancer and lower prostate cancer death rates in regions where PSA testing is more prevalent.
On a global scale, prostate cancer death rates have decreased in countries where PSA screening and active treatment are typically practiced and have remained stable or increased in countries where screening and active treatment are not practiced.
PSA tests are a powerful marker for the risk of developing prostate cancer and dying from it. Reports of over-diagnosis and over-treatment are exaggerated. More often, prostate cancer is diagnosed too late rather than "too early."
If screening detected only harmless cancers, treating them could not produce the striking decline in prostate cancer death rates that has occurred. We should combat the risk of over-diagnosis through continued research for improving the accuracy of screening and high-quality treatment.
This misguided recommendation, and the resulting media coverage, could give reluctant men an excuse to postpone or forgo screening. The consequence might be that many men die of prostate cancer unnecessarily. Men should follow the recommendations of the American Urological Association, the American Cancer Society and the National Comprehensive Cancer Network, all of which recommend screening for early detection and treatment of prostate cancer.
William J. Catalona is medical director of the Clinical Prostate Cancer Program at the Robert H. Lurie Comprehensive Cancer Center at Northwestern University's Feinberg School of Medicine. He receives research support and honorariums for speaking from Beckman Coulter Inc., a manufacturer of PSA tests.