INTEGRIN EXPRESSION IN PRIMARY BREAST-CANCER AND ITS RELATION TO AXILLARY NODAL STATUS

Background. Integrins are transmembrane receptors that modulate cell a dhesion. Each is a heterodimer of varying alpha and beta subunits. In malignancy, loss of integrin expression may result in less adhesive ce lls more likely to metastasize. Our aim was to characterize the integr ins in human breast tissue and to examine the relationship between int egrin expression and nodal metastasis in breast cancer. Methods. Cryos tat sections from 12 benign and 61 malignant (50 ductal and II lobular ) samples were stained by the avidin-biotin complex method with monocl onal antibodies to the beta 1, beta 3, beta 4, and beta 5 subfamilies. All slides were read by two independent assessors with consensus agre ement. Integrin expression was compared to variables by using the chi- squared test with Yates' correction and multivariate analysis based on logistic regression. Results. All integrin subunits studied were sign ificantly reduced on. breast cancer compared with benign cells (chi-sq uared test) but were not related to tumor differentiation. Loss of alp ha 1 beta 1, alpha 2 beta 1, alpha 3 beta 1, alpha 6 beta 1, alpha ups ilon beta 1, and alpha upsilon beta 5 were related to the presence of axillary metastasis. Independently the integrins were of limited clini cal value as Predictors of axillary spread. However, on multivariate a nalysis the combination of beta 1, alpha upsilon, alpha 1, tumor size, and vascular invasion gave a cumulative overall accuracy in predictin g nodal disease of 97%. Conclusions. Integrin expression is reduced in breast cancer and may explain tumor progression. Measuring the integr ins might thus provide a means of selection for aggressive axillary tr eatment.