More Harm than Help from Screening Test for Prostate Cancer
The PSA screening test for prostate cancer causes far more men to undergo unnecessary and harmful treatment than it saves lives, according to two large new studies. As reported by Gina Kolata in the New York Times, one study that followed 77,000 American men for a decade found zero benefit in lowered death rates, while the other study, which followed 182,000 Europeans for nine years, found that only seven lives were saved for every 10,000 men screened with the blood test.
And for every one of those saved lives, forty-eight men were told they had cancer and underwent unnecessary treatment. That treatment can cause impotence or incontinence if it involves surgery, or problems with bowel elimination if it involves radiation.
The problem is not so much the test but the disease. Prostate cancer is usually very slow to grow, and in the cases where it is aggressive, it may already be too late to save the patient when it is discovered.
Both studies were published in the New England Journal of Medicine.
The same issue, on a less dramatic scale, applies to mammography screening for breast cancer. According to Dr. Michael Barry, who wrote an editorial in the NEJM accompanying the research studies, about ten women receive a diagnosis of breast cancer and undergo needless treatment for every one woman whose life is saved after having a mammogram. Breast cancer is much more dangerous than prostate cancer, so screening can still be warranted.
What doctors need, and still do not have, is a way to sort out cancers that would be deadly without treatment from those that would not.
The bottom line for patients is to ask careful questions of your doctor and understand the numbers before you decide whether cancer screening is right for you. Patrick Malone’s new book, The Life You Save, has a chapter that helps patients sort through the statistics of cancer screening.