In April 2014, the U.S. Food and Drug Administration (FDA) approved a human papillomavirus (HPV) test as a primary screening tool for cervical cancer. This meant the test could be used as an initial screen without performing a Pap smear, the established "gold-standard" screening test for cervical cancer. However, the FDA approval did not address how such screening would be applied and some health practitioners may be unsure about adopting such a significant change in their clinical practices.
Persistent infections with high-risk types of HPV (hrHPV) cause almost all cases of cervical cancer. High-risk HPV types 16 and 18 account for about 70% of cervical cancers in the U.S. The hrHPV test detects the genetic material (DNA) of the high-risk types in cervical samples. It can specifically identify HPV-16 and HPV-18 while testing for 12 other high-risk types, such as HPV-31 and HPV-45, at the same time. A Pap smear, alternatively, detects changes in cervical cells that could indicate the presence of pre-cancer or cancer.
Though hrHPV testing is useful for cervical cancer screening, current published guidelines have recommended that it only be used in conjunction with a Pap smear (see Cervical Cancer Screening for Young Adults, Adults and Adults 50 and Up). Data from research studies have been insufficient to recommend hrHPV testing by itself, but the evidence has been accumulating as more studies have been conducted to examine its accuracy as a primary screen.
Now, several major health organizations have come together to offer advice for health practitioners who may be interested in offering the hrHPV test to their patients without a Pap smear. A temporary (interim) guidance was published online on January 7, 2015 in Gynecology Oncology. It was issued in response to the FDA approval and is intended to fill the gap until individual health organizations update their cervical cancer guidelines.
To develop the interim guidance, a panel of experts convened to review some of the latest scientific evidence. Members represented several professional organizations, including the College of American Pathologists, American Society for Clinical Pathology, Society of Gynecologic Oncology, American Society for Colposcopy and Cervical Pathology, American College of Obstetricians and Gynecologists, American Cancer Society, and American Society of Cytopathology.
The panel looked at several large studies that evaluated the effectiveness of hrHPV as a primary screen. Two of the largest studies took place in the U.S. and together involved over a million women. The panel concluded that hrHPV testing can be an alternative to currently recommended primary screening methods.
"Our review of the data indicates that primary [hr]HPV testing misses less pre-cancer and cancer than cytology [Pap smears] alone. The guidance panel felt that primary [hr]HPV screening can be considered as an option for women being screened for cervical cancer," said Warner K. Huh, MD, Division Director and Professor in the Division of Gynecologic Oncology at the University of Alabama, Birmingham in a press release.
Panel members also addressed the follow-up steps that can be taken based on results of an initial hrHPV test. They noted that these are based on limited data currently. Major studies are ongoing, however, and more data are expected soon.
- After a negative result on an initial hrHPV test, a woman should not be re-screened for 3 years.
- A positive result for high-risk type HPV-16 or HPV-18 should be followed up with colposcopy, a procedure in which a health practitioner uses a lighted magnifying instrument to examine a woman's cervix for abnormal areas, to take samples for biopsy, and/or treat as indicated.
- A positive result for the other 12 high-risk HPV types, such as HPV-31 and HPV-45, should be followed up with a Pap smear.
- A positive Pap smear would be followed up with colposcopy.
- A negative Pap smear would prompt follow-up testing in 12 months.
The guidance also notes that primary screening with hrHPV should not be used for women younger than 25. HPV infections are common in this age group and often resolve without treatment. However, women ages 21-25 are recommended to have a Pap smear every 3 years. Screening is not recommended for women younger than 21 or for women older than 65 who have had adequate prior screening.