We also compared features of the five in situ carcinomas (two ER+, two ER− and one with undetermined ER status) of the ATM series with those of the 83 in situ carcinomas from the PICBIM series, and we observed no difference in nuclear grade, tumour size and hormonal status between the two groups of tumours. This evidence concerns the gene ESR1 and in situ carcinoma.