Purpose: In lung cancer patients, radiation therapy modifies lung architecture, resulting in functional deterioration, which worsens symptoms and reduces quality of life.
Methods and materials: 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.
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.
Conclusions: 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.
Trial registration: ClinicalTrials.gov NCT01580579.
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