Clinical Outcomes and Safety Profile in the Treatment of Synchronous Non-Metastatic Lung Tumors with Stereotactic Body Radiotherapy

Abstract

Stereotactic body radiotherapy (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. We queried an institutional database of patients treated with SBRT for primary lung tumors from 2007 to 2019. This cohort represents patients with synchronous primary lesions (either ipsilateral or contralateral); patients with known metastatic disease were excluded. Local recurrence was defined as recurrence within or immediately adjacent to the treated PTV. Regional recurrence was defined as nodal disease recurrence (in the ipsilateral hilum, ipsilateral/contralateral mediastinum, and ipsilateral supraclavicular area). Distant recurrence was defined as disseminated or distant metastatic disease. Recurrences were described as new primaries if they occurred as an isolated pulmonary mass outside the previous PTV. 60 consecutive patients were identified who received SBRT synchronously to ≥2 lesions (126 lesions in total) for non-metastatic lung cancers. 35 patients had biopsy-proven non-small cell lung cancer (NSCLC) in at least 1 of the treated lesions. Median total dose per lesion was 50 Gy (range 30 – 60 Gy), delivered over 3-5 fractions. Regarding clinical outcomes, the median follow-up time was 22 months (range from 1 to 89 months). The median overall survival (OS) and 2-year OS were 23 months and 50%, respectively. 25 of the 60 treated patients (42%) experienced any recurrence, with median time to any recurrence of 14 months. 9 (15%) patients experienced local recurrence, with median time to recurrence of 14 months. 3 (5%) experienced regional recurrence, with median time to recurrence of 30 months. 9 (15%) experienced distant recurrence, with median time to recurrence of 10 months. 13 (21%) developed new primaries, with median time to recurrence of 23 months. Regarding treatment-related toxicities, 27 patients (45%) experienced no toxicity, while 33 (55%) experienced one or more toxicity. 12 (20%) patients experienced CTCAE grade 2 toxicities. 2 patients experienced CTCAE ≥ grade 3 toxicity (pneumonitis and hemoptysis). For patients with synchronous lung tumors treated with SBRT, local control and toxicity appear similar to that of solitary lesions. However, these patients are at a high risk of distant recurrence and new primaries. Further investigation of how to optimize treatment in this group of patients is warranted.