Survival and prognostic factors in patients undergoing the resection of solitary brain metastasis from non-small cell lung cancer: a retrospective cohort study

Background: Neurosurgery is the standard of care for resectable solitary brain metastasis (BM) from non-small cell lung cancer (NSCLC), but still with a poor outcome. Postoperative whole-brain radiotherapy (WBRT) was reported to reduce local recurrence, whether it could prolong survival was uncertain. In this study, we attempted to evaluate WBRT and other prognostic for overall survival (OS) in these patients. Methods: In this retrospective study, NSCLC patients with a solitary BM and controlled primary tumor who underwent neurosurgical resection were selected from the medical records database between January 2014 and December 2018. Clinical data, disease control/progression results and survival outcomes were obtained from the medical records, regular outpatient follow-up and telephone interviews. Univariable and multivariable Cox analyses of potential prognostic factors including patients' characteristics, BM features, tissue-based parameters and postoperative treatments were conducted. OS was illustrated using Kaplan-Meier curves, and group differences were assessed using the log-rank test. The subgroup analysis compared each variable between the WBRT group and the untreated control by the hazard ratio and its 95% confidence interval. Results: A total of 94 patients were included, with a median OS of 812 days. Univariable analysis showed that postoperative WBRT and targeted therapy were associated with OS. Multivariable analysis demonstrated that postoperative WBRT [P<0.001, hazard ratio (HR) 0.357], chemotherapy (P=0.008, HR 0.512), targeted therapy (P<0.001, HR 0.265), and smaller tumor size (P=0.018, HR 0.553) were independent prognostic factors for prolonged OS. However, tissue-based parameters (Ki67 tumor cell proliferation index, epidermal growth factor receptor, and checkpoint levels) were identified as statistically insignificant factors. In the subgroup analysis, the beneficial effect of WBRT was only observed in patients that did not receive systematic treatments. Conclusions: Postoperative WBRT and systematic treatments after solitary BM resection improve the prognosis of NSCLC patients with a controlled primary tumor. Postoperative WBRT could be considered, especially for those who not receive systematic chemotherapy or targeted therapy treatments, as they might be more likely to benefit from it.