A Review of Focal Therapies for Small Cell Lung Cancer Brain Metastases

Small cell lung cancer (SCLC) brain metastases (BM) are common at presentation and relapse. Historically, BM were managed with whole brain radiotherapy (WBRT). However, WBRT is associated with significant toxicity, and so interest in the focal management of BM (focal radiotherapy including stereotactic radiosurgery (SRS) and surgery) is increasing. A systematic literature search of PubMed, Embase, and CENTRAL databases and clinicaltrials.gov was conducted as per the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines to obtain all published articles, abstracts, and ongoing studies regarding focal management of SCLC BM. We identified 59 eligible articles, 6 related to surgical BM treatment (4 case studies, 2 retrospective case studies), and 53 regarding focal radiotherapy (4 case reports, 9 retrospective cohort studies, 32 retrospective case series, 2 prospective cohort trials, 6 ongoing trials). Several trials (n = 6) are ongoing investigating outcomes following focal radiotherapy for SCLC BM, alone and versus WBRT. Whilst limited by their retrospective design, and lack of information regarding local control, first line focal radiotherapy ± WBRT seems to be associated with better survival than WBRT alone. Additionally, salvage focal radiotherapy can achieve 14.3 months median overall survival, outperforming the 3 months median overall survival with salvage WBRT. In highly selected patients, neurosurgical resection of brain metastases may play a role in optimizing local control and/or relieving BM symptoms. Focal treatments for SCLC BM are being used more frequently. However, randomized trial evidence for their safety and effectiveness are still pending.