Human papillomavirus in atypical squamous cervical cytology: The invader HPV test as a new screening assay

In surveillance for cervical neoplasia, a diagnosis of cytologically atypical squamous cells of undetermined significance (ASCUS) presents a significant clinical issue, often dependent on testing for high-risk (HR) human papillomavirus (HPV) for the triage of patients. HPV type 16 now appears to be a critical concern in the follow-up of patients with ASCUS. The Invader HPV (Inv2) test, by Third Wave Technologies, Inc., is a recently developed analyte-specific reagent assay that uses probe sets for the detection of 14 HR HPV subtypes. These probe sets are A5/A6 (HPV types 51, 56, and 66), A7 (HPV types 18, 39, 45, 59, and 68), and A9 (HPV types 16, 31, 33, 35, 52, and 58). This report describes the performance characteristics of the Inv2 test in the screening of ASCUS cervical cytology specimens and correlates the results of the Inv2 test with those of the Hybrid Capture 11 HPV (HC2) test by Digene. The linear array HPV genotyping test (Roche Molecular Systems) was used as a reference method for the testing of samples with discordant results. Ninety-four Pap smear samples with a cytological diagnosis of ASCUS and 39 samples with a negative diagnosis were tested. The results of the Inv2 test demonstrated a good (86.6%) concordance with those of the HC2 test, with an overall sensitivity and specificity of 96% for the Inv2 test. Additionally, the Inv2 assay, which offers high-throughput, semiautomated DNA extraction, allows the subgrouping of HPV types by differential probe sets, could provide a useful test for screening for HPV, and has the potential to provide an improved means of risk stratification and the selection of patients for further HPV subtyping.