Detection of surface antigens defined by monoclonal antibodies in primary mucinous breast carcinomas. Relation to prognostic factors and recurrence-free survival.

Three monoclonal antibodies, 67D11, 115H10 and 115C2, raised against human milk fat globule membranes, have been applied to 207 primary mucinous breast carcinomas. The tumours reacted positively in 18% (67D11), 54% (115H10), and 20% (115C2) of the cases. The detected epitopes (MAM-3a (67D11), MAM-3b (115H10), and MAM-3c (115C2)) have formerly been shown to be markers of differentiation in infiltrating ductal carcinomas. In the present group of mucinous breast carcinomas, statistically significant correlation to high risk factors, such as occurrence of primary lymph node metastases, large tumour size, and local invasion of the tumour into overlying skin or deep fascie, were found. Furthermore, the antigen expression was less marked in pure mucinous carcinomas as compared to carcinomas also presenting with non-mucinous tumour areas. Thus, especially the antigen MAM-3b, is more frequently present in mixed tumours, in large tumours, in tumours with local invasion, and in tumours with primary lymph node metastases. However, no association could be demonstrated between expression of MAM-3b and recurrence-free survival. Mucinous carcinomas of the breast apparently differ from other carcinomas not only with respect to morphology, but also in their pattern of antigenic expression in relation to other prognostic factors.