Estimating prevalence of functional iron deficiency anaemia in advanced cancer

Purpose: Anaemia is a common complication of cancer causing symptoms including fatigue. It is also associated with shorter survival. Cancer causes systemic inflammation which interrupts iron metabolism leading to a functional iron deficiency (FID). There are few data on prevalence or aetiology of anaemia in those with advanced cancer. We aimed to establish the prevalence of anaemia and estimate extent of FID anaemia in patients with advanced cancer. Methods: All patients with advanced cancer referred to two UK specialist palliative care services over 1 year were identified. Demographic and clinical data were linked with routinely collected haematological and biochemical profiles. We assessed the numbers of patients with abnormal values for haemoglobin, % hypochromic red cells (>5% indicates iron-restricted erythropoiesis) and CRP (>10 indicates systemic inflammation). We judged that FID anaemia was likely when patients had all three abnormalities and ferritin 30–800 ng/ml. Results: Out of 2416 patients, 1797 had a cancer diagnosis and laboratory data available. Mean haemoglobin was 116 g/l. Sixty-three percent of patients were anaemic, mild 25%, moderate 35% and severe 3%. Women had significantly higher mean haemoglobin than men, and there was wide variation in anaemia prevalence across tumour sites. Thirty-nine percent of patients who had all four parameters checked met our criteria for FID anaemia. There were significant relationships between haemoglobin, % hypochromic red cells and CRP (p = 0.0001). Conclusions: Anaemia was common in this population, and we estimate this was caused by FID in 66% of anaemic patients. Further research is needed to validate our diagnostic criteria before this approach can be used in clinical practice.