Radiotherapy for oligometastatic tumor improved the prognosis of patients with non-small cell lung cancer (NSCLC).

Background: This study was conducted to investigate if radiotherapy improved the overall survival (OS) of patients with oligometastatic non-small cell lung cancer (NSCLC).

Methods: From January 2012 to August 2015, 323 NSCLC patients with distant metastasis were administered radiotherapy. Ninety-five patients with oligometastatic NSCLC who were sensitive to the initial chemotherapy were treated with radiotherapy for the residual lesions. Initial treatment consisted of four to six cycles of induction chemotherapy. If the patients responded to the initial treatment without developing new metastases, the residual sites were radiated at a total dose of 56-66 Gy, including the primary and metastatic sites. OS, progression-free survival, and sites of progression were assessed. The Kaplan-Meier method was used to estimate the OS and progression-free survival probabilities.

Results: The median survival of the whole cohort was 15 months (95% confidence interval 6-40) and the median time to progression was 11 months (95% confidence interval 4-24). Sixty-seven patients had died by the end of follow-up. The one-year and two-year OS rates were 58% and 23%, respectively. Patients progressed either with brain (n = 14), bone (n = 11), lung (n = 10), liver (n = 7), adrenal gland (n = 5), or seven other sites of metastases (n = 3). Acute grade III esophageal toxicity was observed in 17 patients (18%) and grade III pulmonary toxicity in seven patients (7%).

Conclusion: Oligometastatic non-progressive NSCLC patients may benefit from aggressive radiotherapy to the residual lesions with acceptable toxicity after systemic chemotherapy.