ERBB2 and ductal breast carcinoma in situ: Of note, HER2 gain is not significantly associated with invasive cancer in the univariate analysis, but is inversely associated in the multivariate analysis, in which subjects with HER2 copy number gain were significantly less likely to have an IBC diagnosis (odds ratio 0.47, p = 0.039), when compared to DCIS alone (Table 4).