False Positive

No diagnostic test is perfect, and a false positive is what happens when a test result flags a potential problem that turns out not to be there. In mammography, for example, a radiologist may spot an area of concern that prompts a follow-up ultrasound, additional mammogram views, or a biopsy — only for all those additional tests to confirm that there is no cancer. The initial mammogram result was technically incorrect: it was positive (suggesting concern) but false (the finding was not cancer).

False positives are an inherent feature of population-based screening programs, not a sign that something has gone wrong. When a test is designed to be highly sensitive — meaning it catches nearly every true case of disease — it inevitably also catches some findings that look suspicious but are benign. Radiologists and pathologists work with probability, not certainty, and when a finding falls into an ambiguous gray zone, the appropriate response is almost always to investigate further rather than assume it is nothing.

In breast cancer screening, roughly 10 to 12 percent of mammograms in the United States lead to a callback for additional imaging, and of those callbacks, a much smaller fraction proceed to biopsy. Of biopsies performed following mammogram findings, the majority turn out to be benign. This means that over ten years of annual screening, a woman has roughly a 60 percent chance of experiencing at least one false-positive result — a statistic that underscores the importance of understanding what a callback actually means before one happens.

Receiving a callback after a mammogram or hearing that a test result needs follow-up can be genuinely frightening, and the anxiety that comes with a false positive is real and valid. Research has shown that the worry can persist for months even after a benign outcome is confirmed. Knowing in advance that false positives are common — not rare exceptions — can help you interpret an abnormal result with a clearer head. A callback is a request for more information, not a diagnosis.

At the same time, the possibility of false positives is one reason why screening decisions are personal. Some women prioritize catching every possible cancer as early as possible and are willing to accept the chance of additional testing. Others weigh the anxiety and inconvenience of callbacks more heavily. There is no universally right answer; the goal is a decision that reflects your values, risk profile, and preferences — ideally made in conversation with your doctor before you start screening.