Background Anaemia is common in patients with advanced cancer. Anaemia of chronic disease (ACD)/functional iron deficiency (FID) is the commonest cause, then iron deficiency (IDA), and the two combined (Neoh, Stanworth, Pasricha, et al. Support Care Cancer. 2017;25(4):1209–1214). Distinguishing between types of anaemia guides treatment but criteria vary, so this is challenging (Fletcher, Forbes, Svenson, et al. Br J Haematol. 2022;196(3):523–529).