Combination of Brachytherapy with Iodine-125 Seeds and Systemic Chemotherapy versus Systemic Chemotherapy Alone for Synchronous Extracranial Oligometastatic Non-Small Cell Lung Cancer

BACKGROUND: A proportion of patients with synchronous oligometastatic non-small cell lung cancer (NSCLC) have poor survival, and currently no standard treatment is available, which poses a great challenge to physicians. This study aimed to assess and compare the efficacy and safety of the combination of brachytherapy with iodine-125 seeds and systemic chemotherapy versus systemic chemotherapy alone for synchronous extracranial oligometastatic NSCLC. MATERIALS AND METHODS: After a systematic retrospective review of the case database between 1st Mar 2014 and 30th Mar 2018, data were obtained on 69 NSCLC patients with extracranial oligometastatic NSCLC. Among them, 32 patients received brachytherapy with iodine-125 seeds combined with systemic chemotherapy (group A), and the remaining 37 patients received chemotherapy alone (group B). The primary endpoint was overall survival (OS), and the secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and complications. RESULTS: The demographic and clinical characteristics were not significantly different between the groups (all p>0.05). The overall 3-month ORR was significantly higher in group A (65.6% vs 37.8%, p=0.030) than in group B. With a median follow-up time of 23 months, the PFS and OS were 11.6 (95% CI: 7.0–16.2) months vs 6.3 (95% CI: 3.4–9.2) months (p=0.036) and 17.6 (95% CI: 13.9–21.3) months vs 11.2 (95% CI: 7.7–14.7) months (p=0.042) in groups A and B, respectively. Furthermore, in Cox regression analysis, local brachytherapy was an independent prognostic factor for both PFS (HR=0.416, 95% CI: 0.246–0.702, p=0.001) and OS (HR=0.375, 95% CI: 0.216–0.653, p=0.001). Severe complications were not observed in either of the groups. CONCLUSION: The combination of brachytherapy with iodine-125 seeds and systemic chemotherapy is superior to chemotherapy alone for synchronous extracranial oligometastatic NSCLC.