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Questions to ask before a cancer screening test
Any cancer screening offers the benefits of early detection on one side versus the risks of overtreatment on the other. Patients need to be educated on the pros and cons of any type of screening, and should make the decision along with their doctor. Dr. Michael Barry, president of the Boston-based Informed Medical Decisions Foundation, recommends asking the following questions:
Why should I have this particular test? You should understand your individual risk of getting the disease and, more important, your odds of dying from it over the next 10 years as well as during your lifetime. It may depend on your age, family history, specific genetic patterns, or lifestyle factors like your body weight or smoking status.
Will the test lower my chance of dying from the cancer? If the answer is no, you should press your doctor to name a reason for ordering the screening or skip it altogether. Sometimes, the answer is “we don’t know,” which means studies are lacking or have conflicting results.
What’s the likelihood the test will yield a false result? False negatives [the test fails to detect a tumor] and false positives [the test indicates the possibility of cancer even when none is present] occur with any screening test, so you should ask your doctor to put the number in absolute terms. If you’re concerned about being alarmed by a false finding, that may weigh into your decision to have a screening test with a significant rate of false positives.
What other risks does the test pose? The biggest concern is that a blood test will lead to an overdiagnosis of a cancer that never would have become life-threatening. Often the treatment of these early stage cancers, including surgery or radiation, can cause more harm than the disease itself. Other screening tests like colonoscopies or chest X-rays may pose their own risks.