THE PROGNOSTIC VALUE OF ONCOGENIC ANTIGEN-519 (OA-519) EXPRESSION ANDPROLIFERATIVE ACTIVITY DETECTIVE BY ANTIBODY MIB-1 IN NODE-NEGATIVE BREAST-CANCER

The prognostic value of oncogenic antigen 519 (OA-519) expression and tumour proliferative activity was evaluated in a retrospective series of 118 patients with low-risk breast cancer. Low risk was defined as n egative axillary nodes, tumour diameter less than or equal to 50 mm, a nd no histological evidence of invasion of skin or deep fascia (= T(1) N(0)M(0) and T(2)N(0)M(0)). The median follow-up time was 104 months ( range 5-143 months). Immunohistochemical analysis of OA-519 expression was performed on formalin-fixed, paraffin-embedded tissue. The prolif erative activity was estimated using a Ki-67 equivalent monoclonal ant ibody (MIB-1), which is applicable on formalin-fixed, paraffin-embedde d tissue after microwave pretreatment. OA-519 was expressed in about o ne-third of the tumours and the percentage of proliferating cells (the MIB-1 index) ranged between 1 and 72 per cent (median 17 per cent). U sing multivariate Cox analysis, both the MIB-1 index and OA-519 expres sion were of independent prognostic value (2p less than or equal to 0 . 01), and the combined immunohistological approach may therefore be u seful in selecting patients with node-negative breast cancer who might benefit from adjuvant therapy.