Plasma peroxyl radical trapping capacity in lung cancer patients: a case-control study.

Increasing evidence suggests that cancer patients express oxidative disturbances. The main objective of this cross-sectional case-control study (n = 57 + 76) was to explore whether lung cancer patients, when compared to healthy controls, have alterations in their plasma peroxyl radical trapping capacity (TRAP). Group matching was used with respect to age, sex and smoking history. A secondary objective was to observe the effects of life-long cigarette consumption on plasma TRAP and its components. Mean TRAP values were significantly lower in the cancer patients than in the control group (1143 vs 1273 mumol/l, p = 0.0002). Moreover, all the components of TRAP (except uric acid) were significantly lower in the cancer group: protein SH-groups 442 vs 571 mumol/l, ascorbic acid 34.0 vs 46.5 mumol/l and vitamin E 25.0 vs 33.8 mumol/l. The as yet unidentified antioxidant compounds in plasma contributed 26.5% of plasma TRAP in the cancer group and 30.2% in the control group. There was no correlation between cigarette consumption in pack-years and plasma TRAP; however, plasma concentrations of uric acid and ascorbic acid were negatively correlated with cigarette consumption.