Perera Pin-Yu, Perera Liyanage P, Filkoski Lyvouch, Chen Wen, Lichy Jack H, Paal Edina, Maxwell Jessica H
Pathology and Laboratory Medicine, Veterans Affairs Medical Center, Washington, DC 20422, USA.
National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
World J Oncol. 2020 Feb;11(1):1-8. doi: 10.14740/wjon1243. Epub 2020 Feb 2.
The rise in human papillomavirus (HPV) infection rates over the last few decades in the USA has contributed to a significant increase in the overall incidence of patients diagnosed with squamous cell carcinoma of the head and neck. These head and neck carcinomas develop in the oropharynx, with more than 90% of them caused by infection with high-risk HPV type 16. Patients diagnosed with HPV-induced oropharyngeal squamous cell carcinomas (OPSCCs) have a better prognosis and treatment response than those diagnosed with head and neck cancers caused by alcohol consumption and tobacco use. To identify patients with HPV-positive OPSCC, new guidelines recommend positive staining of oropharyngeal tissues for p16 INK4a (p16) by immunohistochemistry (IHC). Herein we discuss the testing algorithm that was adopted to address discrepant results between p16 IHC and a DNA hybridization (ISH) test used routinely to diagnose HPV-positive OPSCC patients.
A DNA polymerase chain reaction (PCR) test that amplifies HPV16 and HPV18 E7 was developed to aid in the diagnosis of HPV-positive OPSCC in a subset of patients. Specimens from these patients stained positive for p16 by an IHC test, but negative for high-risk HPV by a commercial DNA ISH test. Moreover, these results did not match the histopathological characteristics of the specimens, nor the clinical presentations of the patients.
Of 21 patients' specimens that were tested for p16 by IHC, 11 specimens showed concordant results with the high-risk HPV 16/18 DNA ISH test. Whereas, in eight p16 IHC positive specimens, HPV viral DNA was not detected by HPV16/18 DNA ISH, and two specimens were not tested by DNA ISH. When these eight p16 IHC positive specimens with discrepant p16 IHC and DNA ISH results were further tested by DNA PCR, six specimens showed concordance with p16 IHC with positive results for HPV16 E7, while two specimens were negative for HPV16 E7 by DNA PCR. All tested specimens were negative for HPV18 E7 by DNA PCR. Thus, the addition of the HPV16 and HPV18 E7 DNA PCR test identified a significant number of false negative test results by the HPV16/18 DNA ISH test and likely several false positive results by p16 IHC.
Inclusion of an HPV16 E7 DNA PCR test improved the robustness of HPV-associated OPSCC diagnosis in patients with discrepant results from p16 IHC staining and a DNA ISH test, and identified patients for proper management with less misclassification.
过去几十年间，美国人类乳头瘤病毒（HPV）感染率上升，导致头颈部鳞状细胞癌确诊患者的总体发病率显著增加。这些头颈部癌症发生于口咽，其中90%以上由高危16型HPV感染所致。与因饮酒和吸烟导致的头颈部癌症患者相比，被诊断为HPV诱发的口咽鳞状细胞癌（OPSCC）的患者预后和治疗反应更好。为识别HPV阳性的OPSCC患者，新指南建议通过免疫组织化学（IHC）对口咽组织进行p16 INK4a（p16）染色。在此，我们讨论所采用的检测算法，以解决p16 IHC与常规用于诊断HPV阳性OPSCC患者的DNA杂交（ISH）检测结果之间的差异。
开发了一种扩增HPV16和HPV18 E7的DNA聚合酶链反应（PCR）检测方法，以辅助诊断一部分患者的HPV阳性OPSCC。这些患者的标本经IHC检测p16呈阳性，但经商业DNA ISH检测高危HPV呈阴性。此外，这些结果与标本的组织病理学特征以及患者的临床表现均不相符。
在21例经IHC检测p16的患者标本中，11例标本与高危HPV 16/18 DNA ISH检测结果一致。然而，在8例p16 IHC阳性标本中，HPV16/18 DNA ISH未检测到HPV病毒DNA，2例标本未进行DNA ISH检测。当对这8例p16 IHC和DNA ISH结果不一致的p16 IHC阳性标本进一步进行DNA PCR检测时，6例标本与p16 IHC结果一致，HPV16 E7呈阳性，而2例标本经DNA PCR检测HPV16 E7呈阴性。所有检测标本经DNA PCR检测HPV18 E7均为阴性。因此，增加HPV16和HPV18 E7 DNA PCR检测可识别出大量HPV16/18 DNA ISH检测的假阴性结果以及可能的p16 IHC假阳性结果。
纳入HPV16 E7 DNA PCR检测可提高对p16 IHC染色和DNA ISH检测结果不一致患者的HPV相关OPSCC诊断的稳健性，并减少误诊，确定适合治疗的患者。
