Myth 1: There is no harm in routine cancer-screening tests.
Screening the general population for breast, prostate or other cancers requires weighing the potential benefit of finding a malignant tumor early on—when it is smaller and generally more treatable—against the very real harm of subjecting a lot of people to invasive and/or expensive follow-up procedures that they do not need.
Studies have shown that as many as half of healthy women will receive a false-positive result for breast cancer after 10 years of routine mammogram tests. (A false positive occurs when a diagnostic test tells you that you have a particular ailment, but in reality you do not.) Most of the false-positive group will then have to undergo a more detailed imaging scan and a significant fraction will undergo a biopsy—not to mention dealing with the anxiety of awaiting results.
Mammograms have helped to lower the risk of death from breast cancer. The prostate-specific antigen (PSA) test to screen for prostate cancer, however, cannot even lay claim to such a benefit. Originally developed to help track the recurrence of prostate cancer after the original tumor had already been diagnosed and treated, PSA tests are now widely used as a screening test to pick up unsuspected cases. The only trouble is that two studies (one from the U.S. and one in Europe) have shown that using the PSA test to screen for prostate cancer in this manner does little to decrease death rates in men aged 55 and older. Indeed, the discoverer of PSA has campaigned for years to get people to stop using the PSA test to screen for prostate cancer. (It still makes sense, however, for many men who have a strong family history of the disease or who have actually developed prostate cancer in the past.)
Basically, the more screening tests for different kinds of cancers you undergo, the greater your risk of getting a false-positive result. One study found that half of all people who received at least 14 tests for some combination of prostate, lung, colorectal and ovarian cancer had been given a false-positive result. And men and women with a false-positive test had a one-in-four chance of having to undergo a surgical procedure—with its own attendant risks—to find out that they were okay after all.
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