Immunohistochemical staining of GLUT1 in benign, borderline, and malignant ovarian epithelia

BACKGROUND. Aberrant expression of the facilitative glucose transporter GLUT1 is found in a wide spectrum of epithelial malignancies. The authors describe an immunohistochemical study of GLUT1 expression in benign, borderline, and malignant ovarian epithelia. METHODS. One hundred forty one formalin-fixed, paraffin- embedded sections were immunostained with rabbit anti-GLUT1 using the streptavidin-biotin method. The samples were as follows: 3 endometriotic cysts, 9 serous cystadenomas, 15 mucinous cystadenomas, 17 noninvasive borderline implants, 3 invasive borderline implants, and 3 endosalpingiosis. In addition, 35 borderline tumors (26 serous, 7 mucinous, 2 seromucinous) and 56 adenocarcinomas (50 serous, 4 endometrioid, 2 mucinous) were stained. RESULTS. Benign serous and mucinous cystadenomas and endosalpingiosis were non-staining with GLUT-1 antiserum. Twenty-eight of 35 borderline tumors (80%) stained positively, with weak to moderate (1-2+ out of 3) staining intensity and focal or patchy distribution. Seventeen noninvasive serous borderline implants were negatively stained; however, three invasive serous borderline implants were positively stained with GLUT1 antiserum. Fifty four of 56 ovarian carcinomas (96%) stained positively, with moderate to strong (2-3+ out of 3) intensity and multifocal distribution. CONCLUSIONS. GLUT1 is a consistent marker of ovarian epithelial malignancy. GLUT1 staining is absent in benign ovarian epithelial tumors, and shows progressively more staining in invasive tumors as compared to borderline tumors. AntiGLUT1 antibody may be useful in distinguishing invasive from noninvasive serous borderline implants.