Need for expanded HPV genotyping for cervical screening.

The focus for HPV genotyping has largely been on types 16 and 18, based on their high prevalence in cervix cancer. However screening is focussed on the detection of high grade precursor lesions (CIN3 and CIN2), where other types have a greater role. While HPV16 retains its high predictive value in this context, HPV31 and especially HPV33 emerge as important types with higher positive predictive values (PPVs) than HPV18. Additionally full typing indicates that types 39, 56, 59 and 68 have much lower PPVs than types 16, 18, 31, 33, 35, 45, 51, 52 and 58 and they should be considered as 'intermediate risk' types, whereas type 66 should not be treated as having an increased risk. Available data are summarized to support this view.