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False Positives Common During Cancer Screenings

Posted By Regan Zambri & Long || 18-May-2009

As reported by the Annals of Family Medicine, cancer screening frequently yields false positives — with resulting invasive procedures.

Researchers studied nearly 68,500 adults, aged 55 to 74, who underwent up to 14 screenings over 3 years in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Tests included digital rectal examination plus prostate-specific antigen measurement; chest x-ray; flexible sigmoidoscopy; and cancer antigen 125 testing plus transvaginal ultrasound.
Among the findings:

  • The risk for having one false positive after four tests was 37% among men and 26% among women; after 14 tests, risks rose to 60% and 49%, respectively.
  • The risk for undergoing a false-positive–prompted invasive procedure after four tests was 17% among men and 12% among women; after 14 tests, risks were 28% and 22%, respectively.
  • Sigmoidoscopy accounted for the most false positives and related procedures.

The researchers conclude that providers "should educate patients about the likelihood of false positives and resulting diagnostic interventions when counseling about cancer screening."

Categories: Cancer Misdiagnosis
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