ERBB2 and breast cancer: Screening mammography has given rise to an increased incidence of breast cancer diagnosed at an earlier stage,8 of which an estimated 15% to 20% are considered to be HER2 positive.1 In southern Africa, the incidence of HER2-positive breast cancer is estimated at 25.2%.9 Although data before 2011 were limited by under-reporting from private laboratories, the effect of this was found to be < 4%.10 Because of the cost implications of trastuzumab on a developing economy, only a minority of these patients have access to trastuzumab at any stage of their disease.