Objectives: Reactive oxygen species, which are implicated in the process of carcinogenesis, are also responsible for cell death during chemotherapy (CHT). Therefore, the aim of the study was to evaluate exhaled H2O2 levels in non-small cell lung cancer (NSCLC) patients before and after CHT.
Methods: Thirty patients (age 61.3 ± 9.3 years) with advanced NSCLC (stage IIIB-IV) and 15 age-matched healthy cigarette smokers were enrolled into the study. Patients received four cycles of cisplatin or carboplatin with vinorelbine every three weeks. Before and after the first, second, and fourth cycle, the concentration of H2O2 in exhaled breath condensate was measured with respect to treatment response.
Results: At the baseline, NSCLC patients exhaled 3.8 times more H2O2 than the control group (0.49 ± 0.14 vs. 0.13 ± 0.03 µmol/L, P < 0.05); this difference persisted throughout the study. CHT had no noticeable effect on exhaled H2O2 levels independent of the treatment response (partial remission vs. progressive disease). Pre- and post-CHT cycles of H2O2 levels generally correlated positively.
Discussion: The study demonstrated the occurrence of oxidative stress in the airways of advanced NSCLC patients. Exhaled H2O2 level was not affected by CHT and independent of treatment results and changes in the number of circulating neutrophils.
Keywords: Hydrogen peroxide; chemotherapy; exhaled breath condensate; non-small cell lung cancer.