Adding the p16INK4a Marker to the Traditional 3-marker (ER/Vim/CEA) Panel Engenders No Supplemental Benefit in Distinguishing Between Primary Endocervical and Endometrial Adenocarcinomas in a Tissue Microarray Study:

Application of Immunohistochemistry and Molecular Diagnostics to Clinically Relevant Problems in Endometrial Cancer Bojana Djordjevic, Shannon Westin, Russell R. Broaddus

A number of different clinical scenarios are presented in which lab-based analyses beyond the usual diagnosis based on light microscopic examination of H&E stained slides - immunohistochemistry and PCR-based assays such as sequencing, mutation testing, microsatellite instability analysis, and determination of MLH1 methylation - are most helpful for guiding diagnosis and treatment of endometrial cancer. The central goal of this information is to provide a practical guide of key current and emerging issues in diagnostic endometrial cancer pathology that require the use of ancillary laboratory techniques, such as immunohistochemistry and molecular testing. The authors present the common diagnostic problems in endometrial carcinoma pathology, types of endometrial carcinoma, description of tissue testing and markers, pathological features, and targeted therapy.

Distinguishing between primary endocervical and endometrial adenocarcinomas: is a 2-marker (Vim/CEA) panel enough?

Gynecological pathologists are used to operating many panels of various markers in combination for the diagnostic distinction between primary endocervical and endometrial adenocarcinomas. The conventional 3-marker (ER/Vim/CEA) panel is the most promising tool. In this study, our aim is to investigate whether a 2-marker panel is enough to distinguish between these two gynecologic malignancies. Additionally, we wish to determine which one is the most favorable among eight panels tested, including six 2-marker (ER/CEA, PR/CEA, Vim/CEA, ER/p16(INK4a), PR/p16(INK4a), Vim/p16(INK4a)) and two 3-marker (ER/Vim/CEA, ER/Vim/p16(INK)) panels. A tissue microarray was constructed using paraffin-embedded, formalin-fixed tissues from 35 hysterectomy specimens, including 14 primary endocervical adenocarcinomas and 21 primary endometrial adenocarcinomas. Utilizing the avidin-biotin complex (ABC) method, tissue array sections were immunostained with five commercially available antibodies (ER, Vim, CEA, PR, and p16(INK4a)) to evaluate their individual frequencies of expression. We found that all eight aforementioned panels showed an encouraging range of overall accuracy (69.2% to 78.3%). However, one panel of 2-markers (Vim, CEA) exhibited the most efficiency (78.3%) in the diagnostic distinction between primary endocervical and endometrial adenocarcinomas. Based on the analyzed data, we conclude that the 2-marker (Vim/CEA) panel seems adequate to be an appropriate, convenient, and efficient means to distinguish between primary endocervical and endometrial adenocarcinomas. Even though there were a limited number of cases, this study still provides valuable references to help avoid wasting resources and unnecessary marker testing.

Progesterone receptor does not improve the performance and test effectiveness of the conventional 3-marker panel, consisting of estrogen receptor, vimentin and carcinoembryonic antigen in distinguishing between primary endocervical and endometrial adenocarcinomas in a tissue microarray extension study

Objective

Endocervical adenocarcinomas (ECA) and endometrial adenocarcinomas (EMA) are uterine malignancies that have differing biological behaviors. The choice of an appropriate therapeutic plan rests on the tumor's site of origin. In this study, we propose to evaluate whether PR adds value to the performance and test effectiveness of the conventional 3-marker (ER/Vim/CEA) panel in distinguishing between primary ECA and EMA.

Methods

A tissue microarray was constructed using paraffin-embedded, formalin-fixed tissues from 38 hysterectomy specimens, including 14 ECA and 24 EMA. Tissue microarray (TMA) sections were immunostained with 4 antibodies, using the avidin-biotin complex (ABC) method for antigen visualization. The staining intensity and extent of the immunohistochemical (IHC) reactions were appraised using a semi-quantitative scoring system.

Results

The three markers (ER, Vim and CEA) and their respective panel expressions showed statistically significant (p < 0.05) frequency differences between ECA and EMA tumors. Although the additional ancillary PR-marker also revealed a significant frequency difference (p < 0.05) between ECA and EMA tumors, it did not demonstrate any supplementary benefit to the 3-marker panel.

Conclusion

According to our data, when histomorphological and clinical doubt exists as to the primary site of origin, we recommend that the conventional 3-marker (ER/Vim/CEA) panel is easier, sufficient and appropriate to use in distinguishing between primary ECA and EMA. Although the 4-marker panel containing PR also reveals statistically significant results, the PR-marker offers no supplemental benefit to the pre-existing 3-marker (ER/Vim/CEA) panel in the diagnostic distinction between ECA and EMA.