Are Pap Tests Accurate?

If you follow health news, you might have noticed some controversy over certain cancer-screening methods: Does the evidence support mammograms as a tool to reduce breast cancer deaths? Are PSA tests effective in saving lives from prostate cancer? These are questions that we are beginning to answer as more and more evidence comes in. But don’t let these questions dissuade you from all cancer screening.

With regular Pap testing, cervical cancer is almost 100 percent preventable.

In fact, although we’re reevaluating data for other cancer-screening methods, we have mountains of solid evidence that the Pap test is one of the best cancer-screening methods out there. Because it detects signature mutations that mark cells as headed toward becoming cancerous, Pap testing detects “pre” cancer while other cancer-screening techniques, like mammography, only detect cancer.

Cervical cancer used to be a top killer in developed nations — and it remains a major cause of death in countries without widespread health-care access — but in the last 50 years, cervical cancer deaths fell by 70 percent in the United States, transforming cervical cancer from the leading cause of cancer death among American women to a less common, nearly preventable cancer. Despite this, you might hear people complain that the Pap test isn’t accurate, citing the possibility of receiving “false positive” or “false negative” results.

A Pap test looks for abnormalities in cervical cells, and you can receive one of these four results:

True Positive: Cellular abnormalities are detected, and they are in fact present. True Negative: Cellular abnormalities are not detected, and in fact the cells are normal.
False Positive: Cellular abnormalities are detected, but the cells are actually normal. False Negative: Cellular abnormalities are not detected, but are actually present.

When we receive a true positive result, we can receive treatment for precancerous lesions that in fact might otherwise lead to cancer. Likewise, when we receive a true negative result, no further treatment is needed. Continue reading