ERBB2 and cancer: Since signalling through HER-2 pathways is believed to be involved in driving cell proliferation in ER-negative IBC and to resist anti-oestrogen therapy in ER-expressing/HER-2-positive cancers, the association of COX-2 with HER-2 expression in DCIS suggests that the carcinogenic sequalae of COX-2 overexpression originate at the preinvasive stage in breast carcinogenesis.