Predictors of Respiratory Decline Following Stereotactic Ablative Radiotherapy to Multiple Lung Tumors.
INTRODUCTION
Stereotactic ablative radiotherapy (SABR) is highly effective at controlling early stage primary lung cancer and lung metastases. Although previous studies have suggested that treating multiple lung tumors with SABR is safe, post-treatment changes in respiratory function have not been analyzed in detail.


PATIENTS AND METHODS
We retrospectively identified patients with 2 or more primary lung cancers or lung metastases treated with SABR and analyzed clinical outcomes and predictors of toxicity. We defined a composite respiratory decline endpoint to include increased oxygen requirement, increased dyspnea scale, or death from respiratory failure not owing to disease progression.


RESULTS
A total of 86 patients treated with SABR to 203 lung tumors were analyzed. A total of 21.8% and 41.8% of patients developed composite respiratory decline at 2 and 4 years, respectively. When accounting for intrathoracic disease progression, 12.7% of patients developed composite respiratory decline at 2 years. Of the patients, 7.9% experienced grade 2 or greater radiation pneumonitis. No patient- or treatment-related factor predicted development of respiratory decline. The median overall survival was 46.9 months, and the median progression-free survival was 14.8 months. The cumulative incidence of local failure was 9.7% at 2 years.


CONCLUSION
Although our results confirm that SABR is an effective treatment modality for patients with multiple lung tumors, we observed a high rate of respiratory decline after treatment, which may be owing to a combination of treatment and disease effects. Future studies may help to determine ways to avoid pulmonary toxicity from SABR.
['Moding|Everett J|EJ|', 'Liang|Rachel|R|', 'Lartey|Frederick M|FM|', 'Maxim|Peter G|PG|', 'Sung|Arthur|A|', 'Diehn|Maximilian|M|', 'Loo|Billy W|BW|', 'Gensheimer|Michael F|MF|']
D000328:Adult D000368:Aged D000369:Aged, 80 and over D002289:Carcinoma, Non-Small-Cell Lung D019583:Dose Fractionation, Radiation D005260:Female D005500:Follow-Up Studies D006801:Humans D008175:Lung Neoplasms D008297:Male D008875:Middle Aged D009362:Neoplasm Metastasis D011379:Prognosis D011832:Radiation Injuries D000078703:Radiofrequency Ablation D016634:Radiosurgery D012131:Respiratory Insufficiency D012189:Retrospective Studies D016019:Survival Analysis D055815:Young Adult
Lung metastases Toxicity Dyspnea Radiation therapy Synchronous primary lung cancer