[Assessment of energy expenditure and body composition in cancer patients]

To demonstrate the changes of resting energy expenditure (REE), substrate metabolism and body composition in cancer patients.

From September 2004 to March 2008, REE, carbohydrate oxidation (CO) and fat oxidation (FO) in 936 cancer patients and 840 control subjects were measured by indirect calorimetry. Bioelectrical impedance appliance was applied to assess intracellular fluid, extracellular fluid, fat mass (FM) and fat free mass (FFM) in the two groups.

No difference in REE was found between the cancer patients and non-cancer patients [(1452.2 +/- 196.4) kcal/d vs. (1429.5 +/- 182.6) kcal/d, P = 0.136]. But REE/FFM and REE/pREE were elevated in cancer patients than in controls (all P < 0.05). Of the cancer patients, 48.6% were hypermetabolic, 42.9% normal and 8.5% hypometabolic, while those were 22.5%, 58.5% and 19.0% in controls. Cancer patients had higher FO [(77.8 +/- 11.3) g/min vs. (67.1 +/- 12.1) g/min, P = 0.000], lower CO and npRQ [(68.7 +/- 10.5) g/min vs. (88.8 +/- 12.1) g/min, P = 0.000; 0.782 +/- 0.012 vs. 0.810 +/- 0.014, P = 0.000]. Cancer patients exhibited lower FM and FFM [(14.9 +/- 4.5) kg vs. (18.4 +/- 5.2) kg, P = 0.000; (44.4 +/- 7.2) kg vs. (46.1 +/- 8.1) kg, P = 0.008].

Elevated REE is common in cancer patients. Substrate metabolism of the cancer patients features in increased FO, decreased CO and npRQ, which is correlated with the elevated REE. FM and FFM loses in proportion in cancer patients.