Arch Pathol Lab Med 2020 03 4;144(3):344-349. Epub 2019 Sep 4.
From the Department of Pathology and Laboratory Medicine, Walter Reed National Military Medical Center, Bethesda, Maryland (Dr Keung); Biostatistics Department (Ms Souers) and Proficiency Testing (Ms Vasalos), College of American Pathologists, Northfield, Illinois; Division of Molecular Pathology, The Translational Genomics Research Institute (TGen)/Ashion Laboratory, Phoenix, Arizona, and the Department of Pathology & Microbiology, University of Nebraska Medical Center, Omaha (Dr Bridge); the Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston (Dr Faquin); the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota (Dr Graham); the Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York (Dr Hameed); the Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee (Dr Lewis); the Departments of Pathology and Laboratory Medicine & Genetics, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill (Dr Merker); and Office of the Director, The Joint Pathology Center, Silver Spring, Maryland (Dr Moncur).
Context.—: Detection of high-risk human papillomavirus (HR-HPV) in squamous cell carcinoma is important for classification and prognostication. In situ hybridization (ISH) is a commonly used HR-HPV-specific test that targets viral RNA or DNA. The College of American Pathologists (CAP) provides proficiency testing for laboratories performing HR-HPV ISH.
Objective.—: To compare the analytical performance of RNA- and DNA-based ISH methods on CAP HR-HPV proficiency tests.
Design.—: Data from the 2016-2018 CAP HPV ISH proficiency testing surveys were reviewed. These surveys consist of well-characterized samples with known status for HR-HPV, including 1 to 2 copies, 50 to 100 copies, 300 to 500 copies, and no copies of HR-HPV per cell.
Results.—: Ninety-five participants submitted 1268 survey results from 20 cores. Overall, RNA ISH had a significantly higher percentage of correct responses than DNA ISH: 97.4% (450 of 462) versus 80.6% (650 of 806) ( < .001). This disparity appears to be the consequence of a superior sensitivity of RNA ISH compared to DNA ISH for samples with 1 to 2 and with 50 to 100 copies of HR-HPV per cell: 95.2% (120 of 126) versus 53.8% (129 of 240), < .001, respectively, and 100% (89 of 89) versus 76.3% (119 of 156), < .001, respectively.
Conclusions.—: An assessment of CAP HR-HPV proficiency test performance indicates that RNA ISH shows significantly higher accuracy than DNA ISH owing to higher analytical sensitivity of RNA ISH in tumors with low (1-2 copies per cell) to intermediate (50-100 copies per cell) HR-HPV viral copy numbers. These data support the use of RNA over DNA ISH in clinical laboratories that perform HR-HPV testing as part of their testing algorithms.