Ancillary p16^INK4a adds no meaningful value to the performance of ER/PR/Vim/CEA panel in distinguishing between primary endocervical and endometrial adenocarcinomas in a tissue microarray study

Purpose: Endocervical adenocarcinomas (ECA) and endometrial adenocarcinomas (EMA) are uterine malignancies that have differing biological behavior. The choice of appropriate therapeutic plan depends indeed on the tumor's site of origin. In this study, we not only compare the individual expression status of five immunomarkers (ER, PR, Vim, CEA, and p16^INK4a), but also evaluate whether p16^INK4a adds value to the ER/PR/Vim/CEA panel characteristics in distinguishing between primary ECA and EMA. Methods: A tissue microarray (TMA) was constructed using paraffin-embedded, formalin-fixed tissues from 35 hysterectomy specimens, including 14 ECA and 21 EMA. TMA sections were immunostained with five anti-bodies, by avidin-biotin complex (ABC) method for antigen visualization. The staining intensity and area extent of the immunohistochemical (IHC) reactions were appraised by using the semi-quantitative scoring system. Results: The four respective markers (ER, PR, Vim, CEA) and their combined panel expressions showed significant (p <0.05) frequency differences between ECA and EMA tumors. The p16^INK4a marker also revealed a significant frequency difference (p <0.05) between the two sites of origin, but did not demonstrate to have any supplementary value to the 4-marker panel. Conclusion: According to our data, when there is histomorphological and clinical doubt as to the primary site of origin, we recommend that the conventional 4-marker (ER/PR/Vim/CEA) panel is appropriate. Ancillary p16^INK4a-marker testing does not add value to the 4-marker panel in distinguishing between primary ECA and EMA.