HPV based screening relies on assays that typically detect a pool of 13-14 HPV genotypes associated with cervical cancer. However, the oncogenic potential varies substantially between these types, with HPV16 and HPV18 accounting for over 70% of all cervical cancers, while several other types rarely cause cancer.
Several currently available HPV assays separately detect HPV16/18, and sometimes HPV45, to allow for better risk stratification of a positive HPV result compared to a pooled assay. In some settings, women with HPV16/18 positivity are immediately referred to colposcopy, while women positive for other carcinogenic types are triaged with cytology.
Recent data from large population-based studies suggest that extended HPV genotyping beyond HPV16/18 may be useful in some situations. The remaining HPV types can be separated into two major risk groups, one group that includes HPV31, 33, 45 and several others with intermediate risk and one group, including HPV39, 51, 56 and several others with very low risk.
This separation can allow for more refined risk stratification, particularly in women with minor abnormalities, and could reduce colposcopy referral of women at very low risk.