Immunohistochemical p16 overexpression and Rb loss correlate with high‐risk human papillomavirus infection in endocervical adenocarcinomas

Abstract

Aimsp16 is a sensitive surrogate marker for transcriptionally active high‐risk human papillomavirus (HR‐HPV) infection in endocervical adenocarcinoma (ECA); however, its specificity is not perfect.Methods and resultsWe examined p16 and Rb expressions by immunohistochemistry (IHC) and the transcriptionally active HR‐HPV infection by mRNA in‐situ hybridisation (ISH) with histological review in 108 ECA cases. Thirteen adenocarcinomas of endometrial or equivocal origin (six endometrioid and seven serous carcinomas) were compared as the control group. HR‐HPV was detected in 83 of 108 ECA cases (77%), including five HPV‐associated adenocarcinomas in situ and 78 invasive HPV‐associated adenocarcinomas. All 83 HPV‐positive cases showed consistent morphology, p16 positivity and partial loss pattern of Rb. Among the 25 cases of HPV‐independent adenocarcinoma, four (16%) were positive for p16, and of these four cases, three of 14 (21%) were gastric type adenocarcinomas and one of 10 (10%) was a clear cell type adenocarcinoma. All 25 HPV‐independent adenocarcinomas showed preserved expression of Rb irrespective of the p16 status. Similarly, all 13 cases of the control group were negative for HR‐HPV with preserved expression of Rb, even though six of 13 (46%) cases were positive for p16. Compared with p16 alone, the combination of p16 overexpression and Rb partial loss pattern showed equally excellent sensitivity (each 100%) and improved specificity (100 versus 73.6%) and positive predictive values (100 versus 89.2%) in the ECA and control groups. Furthermore, HR‐HPV infection correlated with better prognosis among invasive ECAs.ConclusionsThe results suggest that the combined use of p16 and Rb IHC could be a reliable method to predict HR‐HPV infection in primary ECAs and mimics. This finding may contribute to prognostic prediction and therapeutic strategy.