Results from a large study confirm that women who test negative for human papillomavirus and who have a normal Pap test when screened for cervical cancer can safely wait 3 years before being retested.
Moreover, the findings strongly suggest that a negative HPV test alone is the more important measure, and could be adequate by itself to extend the testing interval to 3 years.
Investigators deemed the 5-year risk of cervical cancer with a negative HPV test to be "extremely low," at just 3.8/100,000 women per year in the study of 331,818 women who underwent routine co-testing in a managed health plan.
Having a normal Pap test on top of a negative HPV test did not much improve a woman’s chances of not having cervical cancer. The 5-year risk of cancer with good results on both measures was 3.2/100,000 women per year, but the difference between HPV testing alone and co-testing was not significant (P = .8). For all women who had a normal Pap smear, the 5-year risk of cervical cancer with a normal Pap test was 7.5/100,000 women per year (P = .03).
"These findings demonstrate the safety of current guidelines, which recommend a 3-year screening interval for women who test negative for HPV and Pap test," lead author Hormuzd Katki, Ph.D., said during a press briefing at which the American Society of Clinical Oncology offered a preview of studies to be presented at its annual meeting in June.
In addition, "we concluded that a single negative HPV test provided 5 years of extremely low cancer risk for women, and this risk was not appreciably lowered by also having a normal Pap test," said Dr. Katki, a principal investigator in the Division of Cancer Epidemiology and Genetics at the National Cancer Institute.
Screening guidelines from several medical organizations, such as the American College of Obstetricians and Gynecologists and the American Cancer Society, have endorsed concurrent HPV and Pap testing as a safe alternative to Pap testing alone for women aged 30 years and older. These organizations also recommend co-testing every 3 years for women who are HPV negative and have a normal Pap test.
However, there had been no data on the safety of these guidelines in routine clinical practice.
The current study included women aged 30 years and older who enrolled in Kaiser Permanente Northern California’s co-testing program between 2003 and 2005 for 5 years. "I found this to be just a wonderful population-based study from a large real-world experience," said Dr. George W. Sledge Jr., ASCO’s president and Ballve-Lantero Professor of Oncology at Indiana University, Indianapolis.
HPV testing identified more women with a high 5-year risk of cervical cancer or precancer than Pap testing alone. The 5-year risk for HPV-positive women was 7.6%, compared with 4.7% for an abnormal Pap test. "This shows that the HPV test is better able to separate women into categories of high risk of cancer and low risk of cancer," said Dr. Katki. "However, that does not mean that the Pap test is useless. ... When we combine HPV testing and Pap testing, we can get something even better."
For women who tested HPV positive, there were an additional 6 per 100 women who were found to have cervical cancer or precancer if they had a positive Pap test. Most of that extra 6% was found at enrollment in the co-testing program. This "shows that the Pap test is able to identify women who had immediate disease," said Dr. Katki.
"These findings suggest that all HPV-negative women could potentially safely return no earlier than 3 years," he added. Pap testing might be reserved for HPV-positive women. However this will require further testing to verify.
"In the Kaiser population, this would have reduced the number of Pap tests by 95%, and could potentially retain all of the safety of co-testing," said Dr. Katki
The data were provided by Kaiser Permanente and analyzed by researchers at the National Cancer Institute. The authors reported that they have no relevant disclosures.