What does 'specificity' mean in the context of a cancer screening test?

Specificity is the proportion of people who do not have cancer that the test correctly identifies as normal (negative). A test with 99.9% specificity correctly identifies 999 out of 1,000 healthy people as negative, while falsely flagging 1 as elevated (false positive). High specificity is important to avoid unnecessary patient anxiety, invasive follow-up procedures, and healthcare costs. The OncuraKit second-test confirmatory protocol achieves specificity >99.9% — fewer than 1 false positive per 1,000 healthy people tested. On a single test, specificity is somewhat lower (consistent with the zero data overlap in published studies but theoretical false positives from benign conditions). The two-test protocol raises specificity to the reported >99.9% level.