Apoptosis suppressing protein bcl-2 is expressed in well-differentiated breast carcinomas with favourable prognosis

The expression of bcl-2 protein was analysed immunohistochemically in 202 female breast carcinomas. The intensity of bcl-2 expression was inversely related to tumour grade (P<0·0001), tumor necrosis (P<0·0001), mitotic index (P<0·0001), oestrogen receptor content (P<0·0001), progesterone receptor content (P=0·0007), S-phase fraction (P=0·00047), and apoptotic index (P=0·087). A high fraction of bcl-2-positive cells was related to ductal or lobular type (P=0·03) and slight nuclear pleomorphism (P=0·03). Heterogeneous expression of bcl-2 protein was associated with high grade (P=0·02), severe nuclear pleomorphism (P=0·02), DNA aneuploidy (P=0·018), high S-phase fraction (P=0·05), and early metastasis (P=0·03). Intense expression of bcl-2 protein was significantly related to favourable outcome in the entire cohort (P=0·0013), as well as in axillary lymph node-negative (ANN) tumours (P=0·0124). Long recurrence-free periods in the entire cohort (P=0·037) and in ANN tumours (P=0·08) were confined to cases with intense expression of bcl-2 protein. In multivariate analysis, bcl-2 expression had no independent prognostic value in the entire cohort or in axillary lymph node-negative breast carcinomas, whereas it was a weak independent prognostic factor in axillary lymph node-positive breast carcinomas.