The Pitfalls of Common Screening Tests

by Dr. Julian Whitaker
Filed Under: Useless Medicine
Last Reviewed 03/07/2014

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.

Dr. Whitaker’s 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 over-treatment. The U.S. 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. National Cancer Institute guidelines recommend Pap smears once every three years. Most experts agree that women 65 to 70 who have had three normal screening tests in a row and are at low risk can stop having them, as well as those who’ve had a hysterectomy. 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 for cancer risk. Cancer is not caused by a single gene defect, and a positive screening test doesn’t necessarily mean you will get cancer. Moreover, twin studies emphasize the role of lifestyle and environmental factors in development of the disease.

  • 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.

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