Resting energy expenditure in head and neck cancer patients before and during radiotherapy

Weight loss is a frequently observed problem in patients with head and neck cancer (HNC) during radiotherapy. It is still to be assessed whether hypermetabolism is contributing to this problem. The aim of this study was to investigate hypermetabolism before radiotherapy, and changes in resting energy expenditure (REE) in HNC patients during radiotherapy.

REE was measured by indirect calorimetry in 71 patients with HNC before radiotherapy, after 3 and 6 weeks of radiotherapy, and 3 months after radiotherapy. The association between REE and tumour stage, CRP, and prior tumour surgery was analyzed by linear regression analyses. Forty healthy control subjects were one-to-one matched to 40 patients by gender, age and fat free mass (FFM) index to compare REE.

Before radiotherapy, REE was not significantly different between patients and controls, neither in absolute values (1568 ± 247 vs. 1619 ± 244 kcal/d; p = 0.29), nor after weight-adjustment (22.1 ± 3.5 vs. 21.5 ± 3.3 kcal/kg, p = 0.42) or FFM-adjustment (31.5 ± 4.9 vs. 30.7 ± 4.5 kcal/kg, p = 0.38). REE was independent of tumour stage, CRP, and prior tumour surgery. REE (kcal/d) decreased during radiotherapy and thereafter by 9% from pre-radiotherapy (p < 0.01). Weight and FFM also decreased significantly over time (p < 0.001). REE adjusted for FFM decreased in the first 3 weeks of radiotherapy with 4% (B = -1.39 kcal/kg FFM, p < 0.01), increased at the end of radiotherapy and decreased again 3 months after radiotherapy (B = -1.31 kcal/kg FFM, p = 0.04).

Head and neck cancer patients had normal REE before radiotherapy. During radiotherapy, REE decreased continuously with ongoing weight loss. However, weight loss is not the only explaining factor, since REE expressed per kg FFM showed a much more divergent course which is currently unexplained.