Changes in pulmonary function in patients with breast cancer before and after radiation therapy

Abstract

Background: The respiratory system is negatively affected by radiation exposure during the comprehensive treatment of breast cancer (BC), which has an effect on the treatment effectiveness and patients’ quality of life. Objective: To evaluate changes in pulmonary ventilation and diffusion characteristics and ventilation effectiveness in patients with BC before and after radiation therapy (RT). Methods: Our prospective cohort study included 232 women with BC admitted to the Meshalkin National Medical Research Center for an adjuvant RT after surgical treatment. Before and after the RT we conducted pulmonary function tests: body plethysmography, lung diffusion capacity testing, and cardiopulmonary exercise testing with measurement of peak oxygen consumption. We used multivariate regression analysis to determine predictors of pulmonary function decline during RT (decrease in the lung diffusion capacity > 5% compared with baseline). Results: Pulmonary function tests prior to RT demonstrated that 15% of the patients with BC had pulmonary ventilation disorders, and 25% of the patients had pulmonary gas exchange abnormalities (most of them were newly diagnosed). In the general group following RT, we saw a significant decrease in the lung diffusion capacity (P= .044) and an increased incidence of obstructive breathing patterns among the examined patients (P= .036). Other pulmonary ventilation parameters, its effectiveness, and reserve capacity of the respiratory system after RT did not change significantly in the study group and corresponded to the reference values. The postradiation pulmonary function was negatively affected by the reduced level of pulmonary diffusion capacity at baseline (≤ 70% of the reference value) [OR 1.15 (1.03-1.34), P=.004], abnormal breathing pattern prior to RT [OR 1.08 (1.01-1.15), P= .029], involvement of regional lymph nodes (N1-3) [OR 1.10 (1.04-1.26), P= .003]. Conclusion: Early postradiation respiratory disorders in patients with BC are marked by a decrease in the lung diffusion capacity and an increased incidence of obstructive patterns of pulmonary ventilation. The factors negatively affecting changes in pulmonary ventilation and diffusion characteristics after RT were the baseline pulmonary gas exchange disorders, obstructive breathing pattern prior to RT, and radiation exposure to lymph nodes.