HPV testing was statistically significantly more likely to be positive for cancer at any time point, except within 12 months. The analysis found that HPV testing identified more women subsequently diagnosed with cancer and precancer than the Pap test.
Screening histories preceding cervical cancers (n=623) and precancers (n=5,369) were examined to assess the relative contribution of the Pap test and HPV test components in identifying cases. Researchers here quantified the detection of cervical precancer and cancer by cotesting compared with HPV testing alone at Kaiser Permanente, where 1,208,710 women have undergone triennial cervical cotesting since 2003. This remains the most extensive experience of HPV testing incorporated into routine screening in the world. Kaiser Permanente has now screened over a million women by cotesting. In January 2003, just prior to US FDA approval of HPV and Pap test cotesting in mid-2003 and interim guidelines in 2004, Kaiser Permanente Northern California, a large integrated health care organization, introduced three-year cotesting in women aged 30 years and older. Researchers were searching for realistic performance data to quantify the additional benefit of the Pap test component of cotesting, as the costs of intensive screening of all women using two screening tests are substantial. The accumulated evidence supports inclusion of HPV testing in screening thus, the main choice moving forward is between cotesting and primary HPV testing alone. Draft guidelines from the US Preventive Services Task Force recently recommended either primary HPV testing every five years or the Pap test every three years for women 30 to 64, and did not recommend cotesting. Alternatively, current guidelines recommend cotesting but, in recognition of the additional reassurance provided by this approach compared with the Pap test alone, the screening interval is extended to every five years. In the US, an interim guidance issued by a committee of experts from several clinical societies recommended primary HPV testing every three years, the same as the Pap test. Thus, if a single screening method were chosen to complement HPV vaccination, primary HPV testing likely would gradually supplant the Pap test. An HPV test, in which doctors test a cervicovaginal specimen for the presence of the nucleic acids of carcinogenic types of HPV, is more sensitive than the Pap test (a microscopic examination of exfoliated cells) for detection of precancers. However, reports of rare HPV-negative, Pap-test-positive cancers are motivating continued use of both tests (cotesting) despite increased testing costs. The HPV test captures the known cancer causing viruses, but there are gynecologists who believe that there may be unknown cancer causing viruses and so continue to do the Pap smear (plus HPV testing). HPV testing is more sensitive than the Pap test for detecting precancer. But improved screening methods have also introduced some confusion, even controversy.
Despite more research into HPV, and the introduction of preventive HPV vaccines, screening will remain important and comprise many millions of tests annually for decades to come. The Pap test can also find noncancerous conditions, such as infections and inflammation.Ĭervical cancer screening guidelines have changed dramatically over the last 15 years, following introduction of testing for the dozen high-risk human papillomavirus (HPV) types that cause virtually all cervical cancer and its precursors. Cytology-based screening, known as the Pap test or Pap smear, is used to detect abnormal cells. The main goal of cervical screening programs is to detect and treat precancer before cancer develops.
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