BRCA1 expression levels predict distant metastasis of sporadic breast cancers

The role of BRCAI in progression of sporadic breast cancers has to date been equivocal, although preliminary studies on small numbers of samples have suggested an association between expression levels of this gene and acquisition of an invasive phenotype. We have further reasoned that loss of oestrogen receptor positivity may have a detrimental effect on BRCAI expression. In order to test this hypothesis and extend earlier investigations we have applied a sensitive RT-PCR procedure to determine the associations between BRCAI expression and a variety of clinical parameters in a sample cohort derived from sporadic breast tumour specimens. We have established that BRCAI and ER mRNA expression are closely associated (p=0.013), indicating a possible functional relationship between these 2 genes. We have further identified an association between low levels of BRCAI expression and acquisition of distant metastasis in sporadic disease (p=0.019), In light of our findings, we suggest that suppression of BRCAI has a role to play in progression of a significant fraction of sporadic breast cancers and may additionally prove to be a useful, novel, prognostic marker for this disease type. Int. J. Cancer (Pred. Oncol) 84:258-262, 1999, (C) 1999 Wiley-Liss, Inc.