EXPRESSION OF MUC2 EPITHELIAL MUCIN IN BREAST-CARCINOMA

Aims-To examine the expression of the MUC2 epithelial mucin in breast carcinoma; to relate this to patient survival. Methods-Sections from 2 10 breast carcinomas were stained with the anti-MUC2 core protein mono clonal antibody, 4F1, using an immunoperoxidase technique. The proport ion of tumour cells positively stained and the localisation and intens ity of any staining were recorded. Expression of MUC2 was compared wit h histological type and grade, tumour size, presence of nodal metastas es, presence of oestrogen receptors, and menopausal status. The progno stic value of MUC2 expression was examined using Kaplan-Meier survival analysis. Results-MUC2 mucin was detected in 19% of cases of invasive carcinoma, in 11% of cases of carcinoma in situ, where present, but v ery rarely in adjacent normal breast epithelium. Presence of MUC2 was significantly associated with a shorter disease free interval (p < 0-0 5), although the observed difference in duration of overall survival w as not significant. Conclusions-The MUC2 detected in breast carcinoma may be underglycosylated or staining may represent detection of the pr otein core before the completion of glycosylation. The virtual absence of 4F1 reactivity in normal breast epithelium suggests that, unlike t he MUC1 mucin, the MUC2 mucin is not highly expressed by these cells. The mechanism by which expression of MUC2 affects the biology of breas t tumours is unclear, although expression may be a reflection of gener al derepression of genes during tumour progression.