Characteristics of radiation pneumonitis and lung function after curatively intended radiotherapy in non-small cell lung carcinoma

Introduction: We aimed to investigate the characteristics of radiation pneumonitis (RP) and lung function after stereotactic body radiotherapy (SBRT) and concomitant radiotherapy (CRT). These are preliminary data from our prospective study. Material and Methods: We have serial measurements up to 12 months after treatment from 32 inoperable patients with non-small cell lung cancer, treated with SBRT (n=24) and CRT (60-66 Gy with platinum-based chemotherapy) (n=8). The patients were followed with spirometry, total lung capacity measurements, clinical COPD Questionnaire (CCQ) and CT scans. Results: 10 patients in the SBRT group (42%) and 5 patients in the CRT group (63%) developed RP grade 2-4. In our cohort, RP grade 2-4 was diagnosed 6 months (mean) after SBRT and 3 months after CRT. In patients who developed RP after SBRT, the lung function varied over time. Some patients experienced improvement in lung function after treatment, whereas some patients had a reduction. By using T-test, both FEV1% and FVC% were significantly reduced at follow-ups after SBRT. In patients who developed RP after CRT, there was interindividual variation in lung function, and by using t-test, DLCO% were significantly reduced during the follow-up time. Patients without RP and with RP grade 1 after SBRT (n=14) had no significant changes in pulmonary function values. No significant changes were observed in CCQ scores. Conclusion: Pneumonitis after SBRT occur later than after CRT. Although a high percentage of the patients receiving curatively intended radiotherapy developed radiation pneumonitis, this was not reflected in the health related quality of life as measured by CCQ.