Evaluation of the Xpert® HPV assay in the detection of Human Papillomavirus in formalin-fixed paraffin-embedded oropharyngeal carcinomas

Objectives: The increasing incidence of HPV-related Oropharyngeal Squamous Cell Carcinoma (OPSCC) and the improved survival of HPV-positive OPSCC highlight the need for effective tools in evaluating HPV status on formalin-fixed paraffin-embedded (FFPE) cancers. To date, there is no agreement regarding the most appropriate method for HPV testing on FFPE materials. We aimed to investigate the performance of the Xpert® HPV assay (Cepheid) on crude lysates from OPSCC FFPE tissues.

Materials and methods: Crude lysates were obtained by proteinase K digestion of FFPE tissues that had already been analyzed by the INNO-LiPA HPV assay and p16^ink4a immunostaining.

Results: 159 FFPE OPSCCs were evaluated. All the samples provided valid results with the Xpert, whereas three samples (1.8%) were invalid using the INNO-LiPA. Among the remaining 156 cases, 65 (41.7%) were concordantly positive and 87 (55.8%) concordantly negative (raw agreement 0.97, 95% CI: 0.93-0.99; Cohen K 0.95, 95% CI: 0.90-0.99). Type-specific data for the cases that were positive by both methods were completely concordant. Three samples were HPV16-positive with Xpert but negative with INNO-LiPA, while one OPSCC tested negative with Xpert and positive with INNO-LiPA. A very good agreement was observed between the Xpert and the p16 results, which was slightly higher than that for INNO-LiPA (Cohen K 0.87vs. 0.85).

Conclusion: The Xpert HPV assay appears to be a very good method for HPV detection and genotyping on FFPE OPSCCs, and requires no prior purification of nucleic acids. This assay showed a very good agreement with INNO-LiPA and p16 findings.