HPV Genotyping

NorDx would like to announce the new availability of HPV Genotyping. This test allows the detection of specific viral serotypes, in particular HPV types 16 and 18. Existing HPV screening tests detect 14 or 15 HPV oncogenic viral types, however more recent studies (1-3) have demonstrated a significantly higher risk for the presence of a high grade lesion (mostly CIN 3) when the oncogenic virus is types HPV 16 or 18. This is true whatever the cytologic diagnosis is but is especially predictive in women with negative cytology. In fact, the risk of having a high grade lesion in a patient who has a negative cytology exam but is positive for HPV types 16 or 18 is equivalent to having a low grade lesion on Pap smear (approximately 15%). If one restricts the analysis to women over the age of 30, the 10 year risk of developing a CIN 3 or greater is as follows:

• HPV 16 + : 17%
• HPV 18 + : 14%
• HPV High risk screen positive, non- 16,18 type: 3%
• HPV High risk Negative: 1%

For women who are over the age of 30 and a strategy of combined cytology and HPV High Risk Virus testing are utilized, these data suggest that reflexing a positive HPV High Risk Virus Screening result to Genotyping (to determine whether the presence of HPV types 16 or 18 are present) may help identify women at significantly greater risk of harboring or developing a high grade squamous lesion. As a result some authors have recently advocated the use of  HPV genotyping to triage the over 30 patient with a negative cytology result and positive HPV screen. If a reflex HPV genotyping result is positive for HPV 16 or 18, immediate colposcopy is a reasonable option.  Use of HPV genotyping in women < 30 is less clear but has been shown to be predictive of progression to an HSIL in women with LSILs.

For questions or comments, please contact Michael A. Jones M.D. at 662-4038 or jonesm@mmc.org.

1. Khan MJ, Castle PE, Lorincz AT, Wacholder S, et al: The Elevated 10-Year Risk of Cervical Precancer and Cancer in Women With Human Papilloma Virus (HPV) Type 16 or 18 and the Possible Utility of Type-Specific HPV Testing in Clinical Practice. JNCI 97 (14): 1072, 2005.
2. Castle PE, Solomon D, Schiffman M, Wheeler CM. Human Papillomavirus Type 16 Infections and 2-Year Absolute Risk of Cervical Precancer in Women With Equivocal or Mild Cytologic Abnormalities. JNCI 97 ((14): 1066, 2005.
3. Meijer CJ, Snijders PJ, Castle PE.  Clinical Utility of HPV Genotyping. Gynecol Oncol 103: 12, 2006.