very three years, the same as the Pap test. 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. 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.
The accumulated evidence supports inclusion of HPV testing in screening; thus, the main choice moving forward is between cotesting and primary HPV testing alone.
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.
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. Kaiser Permanente has now screened over a million women by cotesting. This remains the most extensive experience of HPV testing incorporated into routine screening in the world.
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. 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.
The analysis found that HPV testing identified more women subsequently diagnosed with cancer and precancer than the Pap test. HPV testing was statistically significantly more likely to be positive for cancer at any time point, except within 12 months. HPV-negative/ Pap test-positive results preceded only small fractions of cases of precancer (3.5%) and cancer (5.9%); these cancers were more likely to be regional or distant stage than other cases.
Given the rarity of cancers among screened women, the contribution of the Pap test to screening translated to earlier detection of at most five cases per million women per year. Two-thirds (67.9%) of women found to have cancer up to 10 years of follow-up at Kaiser Permanente were detected by the first cotest performed.
The researchers conclude that the added sensitivity of cotesting versus HPV alone for detection of treatable cancer affected extremely few women.?
Direct correspondence to:
Division of Cancer Epidemiology and Genetics
National Cancer Institute
To request a copy of the study, please contact: Daniel Luzer
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Oxford University Press USA
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