ERBB2 and breast cancer: However, when including the previous confounding factors in multivariate analysis, MSK1 lost its independent prognostic value for breast cancer-specific survival in both the HER2-negative (hazard ratio = 0.860, 95% confidence interval 0.649–1.141; P = 0.295) and non-basal like subgroup (hazard ratio = 0.938, 95% confidence interval 0.695–1.266; P = 0.674).