ERBB2 and carcinoma: Two thirds of the NST carcinomas showing apocrine differentiation fell in the intermediate and poor IntClusts, with only 10% in IntClust 5 consistent with reported HER2 positivity rates for these tumours.27 Interestingly, mixed-NST and special type tumours predominantly fell in the good prognosis ER + IntClusts 3 and 8, possibly reflecting more indolent underlying molecular biology related to the special type component.