ANALYSIS OF C-MYC MESSENGER-RNA EXPRESSION IN PRIMARY BREAST CARCINOMAS WITH CLINICAL FOLLOW-UP

The level of c-myc messenger RNA was measured in 105 primary breast ca rcinoma samples and matched normal breast tissue from the same patient s. Only tumors showing a greater than 2-fold increase in c-myc levels were considered to be overexpressed. Overexpression of c-myc mRNA was identified in 27.6% of tumor samples analysed and was significantly co rrelated with mitotic grade (p=0.05) and intense lymphocytic infiltrat e (p=0.026) but not with other clinical and pathological variables suc h as size, necrosis, lymph node involvement, estrogen or progesterone receptor status, menopausal status, age or staging of the patients and increased risk of relapse or overall survival. Approximately 25% of t he tumors contained overexpression of c-erbB-2 mRNA and simultaneous o verexpression of the two oncogenes was seen in only five samples. Dise ase-free survival was significantly shorter in these patients (p=0.02) and this reduction remained significant after adjustment for nodal st atus. However, simultaneous overexpression of c-myc and c-erbB-2 did n ot improve significantly the prediction of risk of death.