THE PREVALENCE OF BCL-2 IMMUNOREACTIVITY IN BREAST CARCINOMAS AND ITSCLINICOPATHOLOGICAL CORRELATES, WITH PARTICULAR REFERENCE TO ESTROGEN-RECEPTOR STATUS

BCL-2 protein plays a pivotal role in overriding programmed cell death (apoptosis), thus favouring a prolonged survival of normal and neopla stic cells. Expression of the bcl-2 gene has been documented in some h uman tumours (non-Hodgkin's lymphomas and prostatic adenocarcinomas), but findings in breast carcinomas have not been reported. We have used the monoclonal antibody 124 to investigate BCL-2 expression in 212 br east carcinomas, and to correlate it with the oestrogen (ER), progeste rone (PR) and epidermal growth factor receptor (EGFR) status, and with other clinicopathological variables including tumour type, grade, sta ge, growth fraction (as evaluated by Ki-67 immunostaining), and p53 ac cumulation. Of the 212 carcinomas, 173 (81.6%) exhibited BCL-2 immunor eactivity in more than 25% of the neoplastic cells. BCL-2 immunoreacti vity was strongly correlated with ER and PR expression (P < 0.00001), with the lobular type (P = 0.012) and with better differentiated neopl asms (P = 0.00003), whereas it was inversely correlated with EGFR (P < 0.00001), p53 (P = 0.0004) and Ki-67 (P = 0.0002) immunoreactivities. No association was found with tumour stage (T and N categories). We c onclude that bcl-2 expression in breast cancers is related to the oest rogen-dependent transcription pathway.