HPV Test Does Not Replace Pap Test for Cervical Cancer Screening
By Bryan Tutt
The recent approval of a human papillomavirus (HPV) test for cervical cancer screening has created confusion within the medical community about appropriate screening guidelines.
Unfortunately, some reports of the cobas HPV test’s FDA approval have been misleading. “The media reported this as ‘the Pap test is dead,’” said Andrea Milbourne, M.D., a professor in the Department of Gynecologic Oncology and Reproductive Medicine at The University of Texas MD Anderson Cancer Center. “People are getting the wrong impression.” As a result of this confusion, many patients and even some practitioners are uncertain about the screening guidelines for cervical cancer.
Current screening guidelines
MD Anderson follows the guidelines for cervical cancer screening established by the American Society for Colposcopy and Cervical Pathology in conjunction with the American Cancer Society and the American Society for Clinical Pathology. For those without known risk factors for cervical cancer, the guidelines recommend:
- Women 21–29 years old undergo screening with a Pap test alone every 3 years.
- Women 30–65 years old undergo a Pap test and an HPV test every 5 years.
- Women older than 65 years or who have had a hysterectomy for benign disease do not require screening.
Abnormal findings on a Pap test may require a second Pap test, an HPV test, or an immediate colposcopy, depending on the grade of the lesion.
Proposed screening algorithm
Dr. Milbourne said that in its application for FDA approval, Roche, the manufacturer of the cobas HPV test, proposed the following screening algorithm:
- Women begin screening with an HPV test alone at age 25 years.
- Women with negative tests are retested in 3 years.
- Women who test positive for HPV-16 or HPV-18—the two most common oncogenic strains of the virus—undergo a colposcopy.
- Women who test positive for any of the other 12 oncogenic HPV strains undergo a Pap test.
This screening algorithm was found to be equivalent to cervical cancer screening by Pap test alone in the clinical study that led to the recent approval of the cobas HPV test. However, several issues need to be addressed before the new algorithm can replace or be integrated into the current screening guidelines.
Limitations of screening with HPV test only
One concern about the proposed screening algorithm is that the clinical study compared this algorithm to Pap tests alone rather than the combination of Pap tests and HPV tests currently recommended for women 30 years and older.
Another concern is the limited reliability of HPV testing in women younger than 30 years. “The reason we don’t routinely test for HPV in women under 30 years old is that almost everyone gets exposed to HPV with their first or second sexual encounter,” Dr. Milbourne said. “However, most people in this age group who test positive have transient HPV infections that will resolve without intervention.”
Furthermore, according to Dr. Milbourne, HPV testing is often used inappropriately. “Only about 20% of providers use HPV tests according to FDA-approved guidelines,” Dr. Milbourne said, citing information discussed at the 2014 Biennial Meeting of the American Society for Colposcopy and Cervical Pathology.
Dr. Milbourne said that some providers are inappropriately recommending HPV tests for women younger than 30 years whose Pap tests show high-grade squamous intra-epithelial lesions. “Women with high-grade Pap results should immediately undergo colposcopy,” she said. “As a triage tool, an HPV test should be done when a Pap test shows atypical squamous cells of undetermined significance. If the HPV test is positive, the patient should undergo colposcopy.”
Even as clinicians and researchers work to clarify the roles of the Pap test and HPV tests in cervical cancer screening, HPV vaccination is changing the patient population. Dr. Milbourne said it will take decades to determine the full effect of HPV vaccination on cervical cancer. “It’s new territory,” she said. “We don’t know how sensitive the Pap test is going to be in a vaccinated population. Theoretically, we will need a more sensitive test to screen for cervical cancer as the incidence of HPV gets lower.”
For more information, contact Dr. Andrea Milbourne at 713-745-6986 or view MD Anderson's current guidelines for cervical cancer screening.
OncoLog, July 2014, Volume 59, Issue 7