Scoring of p16(INK4a) immunohistochemistry based on independent nuclear staining alone can sufficiently distinguish between endocervical and endometrial adenocarcinomas in a tissue microarray study

Endocervical adenocarcinomas and endometrial adenocarcinomas are malignancies that affect uterus; however, their biological behaviors are quite different. This distinction has clinical significance, because the appropriate therapy may depend on the site of tumor origin. The purpose of this study is to evaluate four different scoring methods of p16(INK4a) immunohistochemical staining in distinguishing between primary endocervical adenocarcinomas and endometrial adenocarcinomas from limited sizes of tissue specimens. A tissue microarray was constructed using formalin-fixed, paraffin-embedded tissue from hysterectomy specimens, including 14 endocervical adenocarcinomas and 21 endometrial adenocarcinomas. Tissue array sections were immunostained with a commercially available antibody of p16(INK4a). Avidin-biotin complex method was used for antigens visualization. The staining intensity and area extent of the immunohistochemistry was evaluated using the semiquantitative scoring system. Of the four scoring methods for p16(INK4a) expression, Method Nucleus, Method Dominant Cytoplasm or Nucleus, and Method Mean of Cytoplasm plus Nucleus showed significant (P values