Just How Prevalent Are False Positives?
According to an article entitled “The Economic Impact of False-Positive Cancer Screens,” published in Cancer Epidemiology Biomarkers & Prevention in December 2004, of “1,087 prostate, lung, colorectal, and ovarian cancer screening trial participants enrolled in a large managed care organization ... 43% of the study sample incurred at least one false-positive cancer screen.”
This is not to say that periodic cancer scans should not be performed. On the contrary, they are essential to the early detection of cancer. However, the danger arises when a physician insists on a definitive course of action involving potentially dangerous medication, unnecessary and harmful treatments, or surgery on the basis of a single test without alerting the patient to the potential for a false positive.