METALLOTHIONEIN EXPRESSION IN HUMAN BREAST-CANCER

Metallothioneins are ubiquitous low molecular weight proteins characte rised by high cysteine content and affinity for binding heavy metals. Abnormal metallothionein function and expression have been implicated in various disease states, including neoplasia. The aim of this study was to investigate metallothionein expression in human breast carcinom a. Sections of routinely fixed and processed blocks of tumour from 100 consecutive cases of primary operable breast carcinoma were stained f or metallothionein using a recently developed monoclonal antibody and a standard immunohistochemical technique. Expression was scored on the basis of microscopical assessment of percentage of tumour cells stain ing. One patient was lost to follow-up and excluded from the study. A significant association (P<0.0001) was observed between metallothionei n expression and tumour type, with low levels being observed in tumour s of good prognostic type. There was also a significant association wi th local recurrence (P<0.02) and a significant difference (P<0.02) in both survival and disease-free interval between tumours showing low an d high levels of expression, the latter indicating a poor prognosis. N o relationship was observed with patient age, tumour size, lymph node stage, histological grade, vascular invasion, menopausal status or oes trogen receptor status. The assessment of metallothionein expression i n human breast cancer appears to provide prognostic information and ma y have important implications for understanding its development.