Clinical Utility of Extended Genotyping

Recently the FDA approved the BD Onclarity™ HPV assay as a test to identify HPV high-risk genotypes in addition to HPV 16 and 18 (i.e., extended genotyping). The Onclarity assay is designed to identify the 14 high-risk HPV genotypes either individually (HPV 16, 18, 31, 45, 51, 52) or as a pooled mixture of two to three genotypes (HPV 33/58, 35/39/68, 56/59/66). Because different HPV genotypes are associated with different risks of CIN 3, the use of extended genotyping offers a useful tool when following the “risk-based” management strategy recently adopted by the American Society of Colposcopy and Cervical Pathology (ASCCP). For example, when screening using cotesting, women with a NILM cytology result who are positive for HPV 31 have more than twice the 3 year cumulative incidence rate (CIR) for CIN 3 (9%) as HPV 18 positive women (4.4%) and over three times the 3 year CIR for CIN 3 as women with HPV 45, 52, or 33/58 (2.9-2.3%). This suggests that women with NILM who are positive for HPV 16, 31, or 18 should be referred for immediate colposcopy whereas women positive for HPV 45, 52, or 33/58 should undergo repeat cotesting at 12 months. Moreover, women with NILM who are positive for only HPV 56/59/66 have a low enough 3 year CIR (0.3%) that they could simply return for repeat cotesting in 3 years. Extended genotyping can also assist in the management of women with ASC or LSIL cytology. Women with ASC or LSIL cytology who are positive for either HPV 33/58 or HPV 45 have a low enough 3 year CIR (3.7% and 2.1%, respectively) that they could return in 12 months for repeat cotesting rather than undergo immediate colposcopy. As with women with NILM cytology, the 3 year CIR for women with ASC or LSIL cytology who are positive only for HPV 56/59/66 is low enough (0.0%) that they could safely return for repeat cotesting in 3 years.

 

Learning Objectives