Clinical Outcomes and Safety Profile in the Treatment of Synchronous Nonmetastatic Lung Tumors With Stereotactic Body Radiation Therapy

Purpose: Stereotactic body radiation therapy (SBRT) has increasingly been used to treat early-stage primary lung cancers, but its effectiveness and safety in patients with multiple synchronous primary lung tumors is not as well established. Our aim was to evaluate clinical outcomes, patterns of recurrence, and toxicities for these patients.

Methods and materials: We queried an institutional database of patients treated with SBRT for primary lung tumors from 2007 to 2019. Patients with known metastatic disease were excluded. Recurrences were described as new primaries (NP) if they occurred as an isolated pulmonary mass outside the previous planning target volume.

Results: We analyzed 126 lesions from 60 consecutive patients who received SBRT synchronously to ≥2 lesions for nonmetastatic lung cancers. Median total dose per lesion was 50 Gy (range, 30-60 Gy) delivered over 3 to 5 fractions. All but 4 lesions were treated to a biologically effective dose ≥100 Gy. The median follow-up time was 47.3 months (interquartile range, 34.1-65.6). Median overall survival was 46.2 months. Two and 5-year overall survival for all patients was 70% and 48%, respectively. Median progression-free survival was 26 months (interquartile range, 7.6-32.6), and at the time of data collection 25 patients (42%) had experienced any disease progression. Median time to progression was 36 months: 9 (15%) patients experienced local failure, with 1- and 2-year local failure rates of 8% and 13%, respectively. Four patients (7%) experienced regional failure, at 3, 10, 30, and 50 months. Eleven patients (18%) experienced distant failure, with 2-year distant failure rate of 13%. Thirteen patients (21%) developed NPs, with 2-year NP rate of 15.1%. Fourteen patients (23%) experienced Common Terminology Criteria for Adverse Events grade ≥2 toxicity, and 2 patients (3%) experienced Common Terminology Criteria for Adverse Events grade ≥3 toxicity (pneumonitis and hemoptysis).

Conclusions: Synchronous SBRT to biologically effective dose ≥100 Gy appears safe and effective for selected patients with synchronous primary lung tumors.