Society of Clinical Oncology (ASCO) for their interest in our recent study evaluating erythropoiesis-stimulating agent use after changes in Medicare reimbursement policies. 2 We were thrilled that the authors confirmed our findings in patients with breast cancer using CancerLinQ. CancerLinQ has enormous potential and numerous advantages over the existing databases used for health services and comparative effectiveness research, which were well outlined in the letter by Kolacevski et al. It should be noted that all observational studies require sound methodology to reduce selection bias and confounding by indication. We look forward to future opportunities to collaborate with ASCO to use the powerful CancerLinkQ database to understand and improve the quality of cancer care.