We observed increased S100A8/S100A9 levels in blood from patients with ESR1 mutant tumors but given complexity of tumor-cell intrinsic and extrinsic roles of the inflammatory mediators and their receptors (also supported by our single cell sequencing analysis) additional work is needed to understand if and how they contribute to tumor progression in patients with ER mutant tumors. Here, S100A8 is linked to neoplasm.