Patients with head and neck squamous cell carcinoma (HNSCC) and a low level of haemoglobin (Hb) often have a poor response to radiation which may be related to hypoxia induced radioresistance. The aim of the study was to evaluate the prognostic significance of low Hb level and its modification by transfusion in HNSCC patients treated with radiotherapy. The study was performed as a subrandomization in the DAHANCA 5 trial.

Patients were randomized to treatment with the hypoxic radiosensitizer nimorazole or placebo, and in addition, patients with "low" pre-irradiation Hb values (females<13 g/dL; males<14.5 g/dL) were subrandomized to plus or minus transfusion. Transfusion was given with packed red blood cells with the aim to achieve a Hb level in the "high" value range.

A total of 414 patients were included, 243 patients had high Hb levels and 171 patients had low Hb levels. Of the low Hb patients, 82 were randomized to receive transfusion and 89 not to receive transfusion. The treatment arms were well balanced. In the majority of patients, transfusion resulted in increased Hb levels although this tended to decline throughout treatment. Patients with high Hb levels had a significantly better probability of locoregional control, disease-specific survival and overall survival compared to 'low Hb no transfusion' patients. In the low Hb group, transfusion did not improve the outcome in locoregional control, disease-specific survival or overall survival. In multivariate analyses, T and N classifications were significant for all outcome measures, whereas there was no significant influence of transfusion or Hb level on endpoints.

The univariate prognostic significance of high Hb level was demonstrated in patients with HNSCC treated with radiotherapy; however, transfusion prior to and during treatment did not improve the outcome in patients with low Hb values.