You Have to Gamble on Your Health [New York Times 2011-10-10] By H. GILBERT WELCH Hanover, N.H. EARLY October brought two developments in the world of cancer screening: the beginning of Breast Cancer Awareness Month, with its calls for regular mammograms for women, and a new recommendation from the United States Preventive Services Task Force that healthy men not undergo screening for prostate cancer. It¡¯s a stark juxtaposition: screening is good for women and bad for men. But just how different are these two cancer screening tests? The answer is: not very. Neither is like the decision of whether or not to be treated for really high blood pressure. That¡¯s an easy one ? do it. Instead, both breast and prostate cancer screening are really difficult calls, and the statistical differences between them are only of degrees. Reasonable individuals, in the same situation, could make different decisions based on their valuation of the benefits and harms of screening. Personally, as a 56-year-old man, I choose not to be screened for prostate cancer (and, were I female, I believe I would choose not to be screened for breast cancer). Some of my patients have made the same choice, while others choose to be screened. That¡¯s O.K., because there is no single right answer. Screening is like gambling: there are winners and there are losers. And while the few winners win big, there are a lot more losers. It¡¯s easy to understand why. When doctors screen for early cancer, all the incentives ? cultural, financial, professional and legal ? line up in one direction: Don¡¯t miss it. As a result, doctors overreact to even the tiniest abnormalities, which leads to the two basic harms of screening: false-positive tests and overdiagnoses. False positives are really common in both breast and prostate cancer screening. (When it comes to screening, all numbers should be viewed as estimates because the data vary for different populations and practice settings, but numbers do help give a sense of the order of magnitude.) Approximately 15 to 20 percent of women and men who are screened annually over a 10-year period will have to undergo at least one biopsy because of a false-positive mammogram or P.S.A. ? prostate-specific antigen ? test. It¡¯s a matter of opinion to what extent patients with false-positive tests are losers ? the physical complications of biopsies are generally short-lived. But they certainly don¡¯t benefit from the procedures. And in the interim, they¡¯re made to worry that they have cancer. Overdiagnosis is less common, but much more consequential because it leads to unnecessary treatment. Screening finds abnormalities that meet the pathological definition of cancer, yet will never go on to grow or cause any symptoms, let alone death. Sometimes patients choose to wait and see if the cancer grows, but most opt to treat it; once you¡¯re told you have cancer, it¡¯s difficult to wait and see what happens next. Patients who are overdiagnosed are the big losers here. They undergo surgery, radiation and chemotherapy unnecessarily. And then there are the associated complications: chemotherapy can cause nausea and radiation can burn normal tissue; breast surgery can be disfiguring, and prostate surgery can lead to bladder and sexual dysfunction. Doctors don¡¯t know which patients they are treating unnecessarily, but they know how the unnecessarily treated patients got there in the first place ? because they were screened for cancer. Now let¡¯s consider the winners ? those who have avoided dying from breast or prostate cancer by getting screened. While there is some debate about whether they really exist, my reading of the data is that they do, but they are few and far between ? on the order of less than 1 breast or prostate cancer death averted per 1,000 people screened over 10 years. That¡¯s less than 0.1 percent. Overall, in breast cancer screening, for every big winner whose life is saved, there are about 5 to 15 losers who are overdiagnosed. In prostate cancer screening, for every big winner there are about 30 to 100 losers. You may look at these numbers and decide that both tests are good gambles ? or that both are bad gambles. Or you might try to distinguish between the two. Overdiagnosis is more common following prostate cancer screening and is arguably more consequential, as there is a higher risk of long-term complications from prostate cancer treatment. So maybe mammography is the better gamble. Or you might make a different calculation and consider what happens without screening. For breast cancer the first sign is typically a breast lump, which in most cases can now be treated very successfully. (The real success in the war against breast cancer has been improved treatment, not screening.) But the first sign of prostate cancer typically occurs too late for the disease to be treated successfully. So maybe P.S.A. testing is the gamble to take. The truth is that neither test works that well. Even with screening, most people destined to develop deadly, untreatable cancers will still do so. When it comes to breast and prostate cancer screening, there are no right answers, just trade-offs. H. Gilbert Welch, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice, is a co-author of ¡°Overdiagnosed: Making People Sick in the Pursuit of Health.¡±