The National Center for Health Research is dedicated to improving the health and safety of adults and children by scrutinizing medical and scientific research. Based on our detailed analysis of currently available data, the Center strongly supports the existing USPSTF guidelines on cervical cancer screening which recommend Pap smears every 3 years starting at age 21, with the option of replacing that regimen starting at age 30 with a combination of a Pap smear and HPV test.
In response to the key systematic question regarding “the effectiveness of HPV testing, with or without cytology, as a primary screening strategy for reducing cancer mortality and incidence,” we strongly believe that this critical question must be divided into four questions: Is HPV testing effective with or without cytology (Pap smear) for women below 30 and for women above 30? Based on current data, the answers to those four questions seem to differ dramatically and more research will help answer those questions for different racial and ethnic groups.
Based on the research to date, HPV test without cytology should not be used as a screening tool. The HPV test by itself isn’t useful for women under 30 because many young women have HPV that will disappear without any treatment. Being objectively correct about whether HPV is present does not accurately predict whether infection with HPV will lead to cervical cancer. On the contrary, the vast majority of women with HPV will never develop cervical cancer. The only question is the extent to which HPV screening is useful for women over 30 and whether that is related to marital status or other measures associated with the number of sexual partners.
Positive results of an HPV test performed instead of a Pap smear, especially for women under 30, will add anxiety and lead to additional testing, as physicians follow a positive result on the HPV test with a colposcopy, an expensive and invasive procedure that could result in much lower compliance. Undergoing an HPV test without Pap smear is going to scare many women who are not at high or even moderate risk of cervical cancer.
The HPV test can only detect the presence of the virus, which in many cases will not result in cervical cancer; it cannot identify abnormal cells and it also cannot detect cancers of the cervix that are not caused by HPV.
Although the FDA approved the use of the HPV test without cytology in 2014, it did not recommend replacing the safe and effective, well-established Pap screening regimen that has successfully prevented cervical cancer in the U.S. FDA approval does not mean the HPV test is as good as the Pap smear, it only means it is better than placebo.
There has been little comparative effectiveness data comparing HPV-alone screening with HPV and cytology tests, known as co-testing. A new study published last month, conducted by scientists from the Quest Diagnostics laboratory and Magee-Women’s Hospital, analyzed data for over 256,000 women over 30[end Blatt AJ, Kennedy R, Luff RD, Austin RM, Rabin DS. Comparison of cervical cancer screening results among 256,648 women in multiple clinical practices. Cancer Cytopathol. 2015 May;123(5):282-8. Epub 2015 Apr 10.], and found that “approximately 19% of women with cervical cancer may be misdiagnosed by an HPV-only cervical screen.” We urge the USPSTF to carefully review those data, and compare them to co-testing for women under 30 and those over 30.
The study data support co-testing in women ages 30 to 65 years as more effective at detecting pre-cancers and cancers. In addition, the study states that, “Co-testing performed better than HPV-alone or Pap-alone for cervical adenocarcinoma, a form of cervical cancer that is known to be harder to detect”. It is important to consider and carefully scrutinize these data as the guidelines for cervical cancer screening undergo revision. We ask that USPSTF includes this study in its Proposed Research Approach — Evidence Review.
Current data indicate that HPV testing alone is likely to be much less accurate on women under 30, making the benefits of co-testing less likely for that age group.
In conclusion, based on current data and an excellent track record in the U.S., we believe Pap smear is an important screening tool, and that women should continue to rely on it every 3 years starting at age 21. Pap smears identify abnormalities in the cervix, which is useful by itself or together with an HPV test for women over 30. Most U.S. women who get cervical cancer did not have Pap smears within the last 5 years. In fact, some never had Pap smears. For that reason, women should continue to rely on Pap smears to screen for cervical cancer. At the age of 30 or older, women may want to also be tested for HPV at the same time.