GLUT1 GLUCOSE-TRANSPORTER - A HIGHLY SENSITIVE MARKER OF MALIGNANCY IN BODY CAVITY EFFUSIONS

Malignant cells exhibit increased rates of glycolysis and glucose upta ke, and several types of cancer have been reported to overexpress the GLUT1 glucose transporter. The diagnosis of malignancy in body cavity effusions remains a dilemma in certain cases, despite recent progress in diagnostic immunocytochemistry. We used immunostaining to detect th e facilitative glucose transporter, GLUT1, in cytologic preparations o f body cavity effusions and washes. With the use of standard avidin-bi otin immunostaining for GLUT1, we examined cell blocks of body cavity effusions or washings from 31 carcinomas, 1 lymphoma, and 25 benign ef fusions or washes. GLUT1 staining occurred in the malignant cell popul ation in 29 (93.5%) of 31 carcinomatous effusions or washes. The chara cteristic staining pattern. consisted of dense, linear staining of the plasma membrane, with accentuation at cell-cell borders, wills or wit hout cytoplasmic staining. Erythrocytes showed positive GLUT1 membrane staining, consistent with previous reports. Of 25 benign effusions, 2 0 were nonstaining (excepting erythrocytes), and 5 contained rare sing le mesothelial cells, with equivocal to very weak membrane staining. S taining of these cells was readily distinguishable from the characteri stic strong staining of malignant cells, and these cells were easily d istinguished from tumor cells by their benign morphologic characterist ics. At least three of these latter five specimens were from patients with cirrhosis, In all of the other eases, mesothelial cells, histiocy tes, and other inflammatory cells did not stain. These findings sugges t that GLUT1 immunostaining could be useful in diagnostic cytopatholog y. The findings also suggest that enhanced glycolysis, which requires increased glucose transport, might be a survival adaptation for tumor cells in effusions, a significant number of which are hypoxic.