In HR−/HER2+ breast cancer, MMP11 (hazard ratio 1.49; 95% CI 1.08–2.04; P = 0.014) and CD2 (hazard ratio 0.66; 95% CI 0.47–0.94; P = 0.022) retained their statistical significance for DMFS in multivariate analysis. Here, CD2 is linked to breast cancer.