Overview of the Pap Test

Several different observational reports suggest that the Pap (Papanicolaou) test is highly effective in lowering the risk of death among women with cervical cancer. Pap tests allow women to receive cervical cancer diagnoses early, so they can get the proper treatment to slow down the cancer’s progression.

Modern cervical cancer screening programs have only gotten better and contributed to reducing cervical cancer deaths in populations worldwide. For instance, Iceland has experienced an 80% decrease in its population’s death rate among those with cervical cancer. Sweden also reduced its cervical cancer-based death rate by 34%. Countries like Canada and the United States have also seen similar reductions in cervical cancer-related deaths. These cancer death decreases are due to increased cervical cancer screenings worldwide.

Several case-control medical studies discovered that women have a 3 to 10 times greater chance of forming invasive cervical cancer if they do not get screened for cervical cancer. In addition, a woman’s risk of developing cervical cancer will also increase if she remains untested for too long after her last normal Pap test screening. Frequent cancer screening is needed to catch the early indicators of cervical cancer. Most health experts recommend a woman get a Pap test every 2 or 3 years.

Does the Pap Test Provide Accurate Results?

Determining the accuracy of a cervical screening test, such as a Pap test, requires evaluating the specificity and sensitivity of the results. Doctors usually perform a “gold standard test” to study the accuracy of any cervical cancer screening test. The gold standard test involves performing a colposcopy and a necessary biopsy of various participants in the test study.

During the screening tests of the participants, the doctors will calculate the percentage of cases found to be true-positive (sensitivity) and the percentage of cases found to be true-negative (specificity). Although gold standard tests are often not performed on cervical cancer screening tests, they have been done on people who have undergone repeat Pap testing.

The results show that the sensitivity percentage for discovering high-grade cancerous lesions in participants who took only one test is between 55% to 80%. But those who received more frequent testing had a much higher sensitivity percentage. The reason is that cervical cancer growth is slow in nature, so it requires more frequent testing to detect it.

However, a reference-standard threshold and test threshold must be defined before determining a Pap test’s sensitivity and specificity. The thresholds are achieved when the test and reference reach a positive result. The normal practice is to use CIN 1 for the reference threshold and atypical squamous cells of undetermined significance (ASCUS) for the test threshold. Combining both thresholds produces a 75% specificity and 68% sensitivity for the results.

Of course, the obtained specimen must be adequate for the Pap test to have a high level of accuracy. Sensitivity can also be improved if proper training and techniques, including the cytobrush, are used.