The Pitfalls of Common Screening Tests

Filed Under: Useless Medicine
Last Reviewed 09/04/2015

The Pitfalls of Common Screening Tests

study published in the Journal of the American Medical Association shows annual ovarian cancer screening tests don’t lower women’s risk of dying from the disease, but they do expose them to more health risks from unnecessary invasive treatments. This is a prime example of conventional medicine’s dark side that all too often harms rather than heals.

So which tests should you get and when should you get them? It depends on who you listen to. Unfortunately, there’s no clear consensus among expert panels and advocacy groups, so confusion reigns.

I hesitate to make blanket recommendations. However, before you have a screening test, I strongly encourage you to understand both the pros—the slim but potentially lifesaving possibility that early-stage, clinically significant cancer will be found and treated—and the cons—the high risk of false positives, additional testing, anxiety, and unnecessary treatment. That way, you’ll be better prepared to deal with the outcome, whatever it may be.

Screening Test Recommendations

  • PSA for prostate cancer. PSA is the most controversial of all screening tests because of very high false positive rates and rampant overtreatment. The US Preventive Services Task Force has concluded that “the current evidence is insufficient to assess the balance of benefits and harms of prostate cancer screening in men younger than age 75 years.” In August 2008, this group also urged physicians to stop testing PSA in men 75 and older.

  • Mammograms for breast cancer. Mammograms carry the most emotional baggage—it’s downright unpatriotic to badmouth these screening tests. Several randomized controlled trials have looked at screening mammography. Some support its utility, some don’t. More than one in two women who have yearly mammograms for 10 years will have a false positive. Furthermore, many of the cancers detected and unnecessarily treated are small, slow-growing or nonprogressive cancers that you’d never know existed were it not for screening tests.

  • Fecal occult blood tests and colonoscopy for colon cancer. Three randomized studies suggest that fecal occult blood tests lower chances of dying from colon cancer by 15 percent to 30 percent. However, false positives are very common. Regarding colonoscopy, the Preventive Services Task Force has concluded, “It is unclear whether the increased accuracy of colonoscopy … offsets the procedure’s additional complications, inconvenience, and costs.”

  • Pap smears for cervical cancer. Over the years, the American Cancer Society has gone from recommending yearly Paps to “after three or more consecutive satisfactory normal annual the discretion of the physician.” Also, women over age 65 who have had a series of normal Paps are at extremely low risk and no longer need to be tested. Also, be aware that lifetime false positive rates are extremely high and that many doctors inexplicably order Pap smears annually for women of all ages.

  • Chest X-rays for lung cancer. Three clinical trials have shown that routine chest X-rays do not reduce risk of death from lung cancer. No group stands behind routine screening tests at this time.

  • Genetic tests. There are several genetic tests available. Some claim to predict the chances of developing certain diseases, and others offer advice in lifestyle changes based on your genetic profile. While I fully support learning all you can about health risks, I have a few concerns about these tests. First, genes are not destiny. There is a great deal of interplay between genes and environment. So if people use the results of genetic tests to modify diet and other behaviors that would protect them against diseases they are genetically predisposed toward, great. If this information makes them feel they have a date with disaster or death, it’s not ideal.

  • Other cancer screening tests. Other screening tests that have yet to be shown in randomized trials to save lives include ultrasounds and CA-125 for ovarian cancer, skin exams for melanoma, and head and body scans for cancer of the brain and abdomen.

DISCLAIMER: The content of is offered on an informational basis only, and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified health provider before making any adjustment to a medication or treatment you are currently using, and/or starting any new medication or treatment. All recommendations are "generally informational" and not specifically applicable to any individual's medical problems, concerns and/or needs.

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