Longitudinal Evaluation of Lung Function in Patients With Advanced Non-Small Cell Lung Cancer Treated With Concurrent Chemoradiation Therapy.

Abstract

In lung cancer patients, radiation therapy modifies lung architecture, resulting in functional deterioration, which worsens symptoms and reduces quality of life. A multicenter, prospective, longitudinal study was conducted in a cohort of patients with locally advanced and oligometastatic non-small cell lung cancer treated with concurrent chemoradiation therapy (CCRT). A wide array of pulmonary function tests (forced spirometry, body plethysmography, impulse oscillometry, carbon monoxide diffusing capacity, fraction of exhaled nitric oxide, arterial blood gases, and 6-minute walk test) were used to evaluate lung function at baseline; after radiation therapy; and at 6, 12, 24, and 48 weeks after CCRT. Relative changes in test results (percentages) were estimated at the aforementioned intervals and compared with baseline results. Thirty-seven patients completed the follow-up and were included in the analysis. After CCRT, patients showed a maximum decline in lung volumes as follows: (1) 31% in forced expiratory volume in the first second after 24 weeks (P = .008), (2) 9.6% in forced vital capacity after 48 weeks (P = .04), and (3) 15.1% in total lung capacity after 48 weeks (P = .0015). Similarly, at 12 weeks after CCRT, patients showed a 21.8% decrease in carbon monoxide diffusing capacity (P = .002). Increases were found in total airway resistance (respiratory system resistance at 5 Hz), frequency dependence of resistance (change in respiratory system resistance at 5 Hz-respiratory system resistance at 20 Hz, P = .012), and reactance (P = .0003 for respiratory system reactance at 5 Hz and P = .001 for reactance area), which together indicate small-airway dysfunction. The longitudinal evaluation of lung function through pulmonary function tests detects CCRT-induced damage before the appearance of clinical symptoms associated with CCRT lung toxicity.