Determination of c-myc amplification and overexpression in breast cancer patients: evaluation of its prognostic value against c-erbB-2, cathepsin-D and clinicopathological characteristics using univariate and multivariate analysis

C-myc and c-erbB-2 amplification and/or overexpression as well as total cat hepsin-D (GD) concentration have been reported to be associated with poor p rognosis in breast cancer. The prognostic significance, however, remains so mewhat controversial, partly because of discrepancies among the different m ethodologies used. We determined the amplification and overexpression of c- myc oncogene in 152 breast cancer patients and examined its prognostic valu e in relation to c-erbB-2 amplification and overexpression, high concentrat ion of CD (greater than or equal to 60 pmol mg(-1) protein) and standard cl inicopathological prognostic factors of the disease, High CD concentration, as well as c-myc amplification and overexpression, proved to be the best o f the new variables examined for prediction of early relapse (ER; before 3 years). After multivariate analysis only CD remained significant, which sug gests that the prognostic power of these variables is similar. Using univar iate analysis we proved that c-myc amplification and overexpression were hi ghly significant for disease-free survival (DFS) (P = 0.0016 and P = 0.0001 respectively) and overall survival (OS) (P < 0.0001 and P = 0.0095 respect ively), although by multivariate analysis c-myc overexpression was statisti cally significant only for DFS (P = 0.0001) and c-myc amplification only fo r OS (P = 0.0006). With regard to c-erbB-2, only its overexpression appeare d to be significant for DFS and OS, although after multivariate analysis it s prognostic power was weaker (P = 0.030 and P = 0.024 respectively). c-myc amplification and overexpression exhibited a tendency for locoregional rec urrence (LRR) (P = 0.0024 and P = 0.0075 respectively), however, their prog nostic value was lower after multivariate analysis and only CD remained sig nificant. (C) 1999 Cancer Research Campaign.