ERBB2 and neoplasm: In the analysis comparing BRCA1 tumours with sporadic tumours, the factors in the final model were ER (for negative status: odds ratio [OR] = 11.2, 95% confidence interval [CI] = 4.3 to 29.2), HER2 (for negative status: OR = 4607.4, 95% CI = 0 to 3.8 × 1021) and age at onset (for age <50 years: OR = 4.3, 95% CI = 1.6 to 11.2).