[Hemoglobin and fatigue in cancer patients: inseparable twins?]

Tiredness is one of the most common symptoms in patients with cancer, and, because of its multifaceted manifestation in this population today, it is generally termed the "fatigue syndrome". Causal relationships are complex and multidimensional. Research suggests that the type and stage of cancer play an important role, and that side effects of cancer treatment as well as psychological factors may be involved. A causal relationship between fatigue and a certain degree of anaemia has been suggested. Whilst it is acknowledged that severe anaemia causes "fatigue", the influence of mild, chronic anaemia on quality of life is not yet clear. It is the aim of this prospective, descriptive study to investigate the correlation between "fatigue" in cancer patients and their haemoglobin levels. Haemoglobin was measured in 444 cancer patients with different types and stages of cancer and treatment modalities. Concurrently, fatigue was assessed with the new Fatigue Assessment Questionnaire (FAQ). In addition, the Karnofsky Index was assessed and depression and anxiety were measured with the Hospital Anxiety and Depression Scale.

Cancer patients with a haemoglobin level below 11 g/dl suffered from fatigue more than patients with higher haemoglobin levels (r = -0.196, p < 0.001). The correlation of "fatigue" was most prominent with physical fatigue such as reduced physical performance or weakness. The Karnofsky Index correlated significantly with the haemoglobin concentration. Patients with lower haemoglobin levels showed more signs of depression than those with higher levels.

The grade of anaemia correlates with intensity of fatigue in cancer patients and also with depression. Both can be related to the advanced disease situation. Data suggest that if levels of haemoglobin are lower than 11 g/dl, subjective fatigue should be specifically assessed to plan treatment according to the patients' need. It remains to be substantiated when and which treatment is indicated to alleviate fatigue and to support quality of life in the individual anaemic cancer patient.