Long-Term Survival without Systemic and Immune Therapy after Synchronous Thoracic and Brain Stereotactic Radiation for Oligometastatic NSCLC

Abstract

There is increasing interest in treating oligometastatic non-small cell lung cancer (NSCLC) with stereotactic radiation. We aimed to address whether patients with NSCLC who were treated with synchronous thoracic stereotactic body radiation therapy (SBRT) and brain stereotactic radiosurgery (SRS) had favorable outcomes with local therapy alone. We reviewed an institutional review board-approved prospective database of patients receiving thoracic SBRT between June 2004 and January 2016 for those with cT1-2aN0 NSCLC as well as a database for brain metastasis patients treated with SRS. All patients opted in and signed an informed consent document for inclusion. Oligometastatic patients had thoracic SBRT and brain SRS within 90 days. Their overall survival (OS), freedom from progression (FFP), and both thoracic and brain local control (LC) were calculated from the date of first radiation therapy fraction and compared to outcomes for cT1-2aN0M0 patients. Patients who died of causes other than disease progression or treatment complications were censored and not counted as progression or local failure. Six patients had oligometastatic NSCLC with 1-3 synchronous brain metastases treated with lung SBRT and brain SRS. 645 patients had stage I NSCLC treated with lung SBRT alone. None of the oligometastatic patients had immunotherapy and two-thirds did not receive systemic therapy. Median follow-up was 24 months (range, 1-153 months) for the stage I group and 9 months for oligometastatic group (range, 2-95 months). Median OS was 41 months (95% confidence interval [CI], 37-45 months) in the stage I group compared to 12 months (95% CI, 5-18 months) in the oligometastatic group. At 1 year, stage I patients had 86% OS (95% CI, 83-89%), 80% FFP (95% CI, 77-84%), and 92% LC (95% CI, 90-95%). At 1 year, oligometastatic patients had similar OS (50% [95% CI, 10-90%, P=0.18]) and LC (100% [P=0.51]) with decreased FFP (17% [95% CI, 0-47%, P<0.001]). Their brain disease had 80% 1-year LC (95% CI, 45-100%) and 53% 1-year FFP (95% CI, 5-100%). The 5-year OS in the oligometastatic group was 17% (95% CI, 0-47%). Two of the patients had no distant progression: one remains alive at 95 months and the other died at 1.8 months. Of the remaining patients, two had progression in their brain at 2.3 and 10.1 months, one had progression to their adrenal gland at 6.8 months, and one had progression to their vertebrae, femur, and liver at 5.7 months. In patients presenting with oligometastatic lung cancer limited to the brain who are not candidates for systemic or immune therapy, aggressive treatment with both lung SBRT and brain SRS achieves good LC of all sites with encouraging OS. We observed no statistically significant difference in OS compared to patients with stage I disease, though this is limited by patient numbers.