HPV testing of biobanked liquid-based cytology - a validation study

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Abstract

Introduction:

The aim of the study was to investigate whether biobanked liquid-based cytology (LBC) vaginal samples could be reanalyzed for the biomarkers HPV DNA and mRNA without loss of sensitivity.

Methods:

One hundred LBC samples with ASCUS or CIN1 were tested for HPV DNA and mRNA before and after biobanking. DNA analysis targeted the viral genes E6 and E7, 12 high-risk and 2 low-risk HPV types together with the human control gene HBB, using real-time PCR. The Aptima HPV assay was used for mRNA analysis of 14 high-risk HPV types.

Results:

With Aptima there was 84% agreement between results before and after biobanking. The sensitivity and specificity were 0.79 (95% CI, 0.68-0.88) and 0.94 (95% CI, 0.80-0.99), respectively. With the DNA-based method, the agreement between results was 87%, the sensitivity 0.85 (95% CI, 0.75-0.92) and the specificity 0.95 (95% CI, 0.77-1.00). Both methods presented a significant difference between positive results before and after biobanking; McNemar test: p = 0.004, p = 0.003, Cohen's kappa: 0.67 (95% CI, 0.53-0.81), 0.68 (95% CI, 0.52-0.84). Cycle threshold values for the DNA method were higher for all genotypes after biobanking, except for HPV-59. Some loss of sensitivity was seen after biobanking but the concordance between HPV detection before and after biobanking was good for both evaluated methods.

Conclusions:

Biobanking of LBC vaginal samples offers a good platform for HPV testing and could be extended to further molecular analyses. However, in order to ensure a valid test result a larger portion needs to be analyzed from the biobanked sample.

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