Patients with a CCI score of 0 had clinically meaningful and statistically significantly higher mean GHS/QoL scores than patients with a CCI score of 3+ at each assessment.<h4>Conclusions</h4>Patients with HR+/HER2- ABC receiving palbociclib with higher comorbidity burden, especially blood and lymphatic system disorders, had poorer clinical outcomes. This evidence concerns the gene ERBB2 and lymphatic system disorder.