ERBB2 and cancer: However, we did not observe a significant association between EFS and ROR1 among patients with HR + HER2- tumors who had little or no post-treatment residual cancer burden (RCB-0/I) (HR = 1.85, 95% CI = 0.74–4.61, LRp = 0.19), which may in part be attributable to a smaller number of events within the RCB-0/I group.