Abstract
Lung cancer is the second most common cancer and the most common cause of cancer-related death in the United States. Brain metastases (BM) are detected in 21% of patients with lung cancer at the time of diagnosis and are the sole metastatic site in 35% of patients with stage IV disease. The best upfront therapy for non-small-cell lung cancer depends on both tumor programmed death 1 ligand-1 (PD-L1) expression and the presence or absence of a targetable genetic alteration in genes such as epidermal growth factor receptor and anaplastic lymphoma kinase. In the absence of a targetable genetic alteration, options include chemotherapy, immune checkpoint inhibitors (ICIs), and ICI combined with chemotherapy. Upfront local therapy followed by systemic therapy is the current standard of care for the management of BM, and may include whole brain radiotherapy, stereotactic radiosurgery (SRS), or craniotomy for surgical resection followed by consolidative SRS. This paradigm is effective in achieving local control, but it remains unclear if this approach is necessary for every patient. Prospective and retrospective data suggest that ICIs with or without chemotherapy can have activity against BM; however, appropriately selecting patients who are able to safely forgo local therapy and start an ICI-based treatment remains a challenge. To be considered for upfront ICI-based therapy, a patient should be free of neurologic symptoms, lesions should be small and not located in a critical region of the central nervous system, if corticosteroids are indicated the requirement should be low (prednisone 10 mg/d or less), and PD-L1 expression should be high. The decision to proceed with upfront ICI without local therapy to BM should be made in a multidisciplinary fashion and patients should undergo frequent surveillance imaging so that salvage local therapy can be administered when necessary. Prospective clinical trials are needed to validate this approach before it can be widely adopted.