Clinical Value of Upfront Cranial Radiation Therapy in Osimertinib-Treated Epidermal Growth Factor Receptor–Mutant Non-Small Cell Lung Cancer With Brain Metastases

Purpose As a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), osimertinib has a powerful ability to penetrate the blood-brain barrier and a high potency for controlling brain metastases (BMs) from EGFR-mutant non-small cell lung cancer (NSCLC). The clinical value of cranial radiation therapy in osimertinib-treated NSCLC with BMs remains largely unknown. Methods and Materials Patients with NSCLC and BMs and receiving osimertinib treatment as the standard of care were retrospectively enrolled from 2 institutions. Cranial radiation therapy (RT; whole-brain radiation therapy [WBRT] or/and stereotactic radiosurgery [SRS]) performed before disease progression (PD) to osimertinib was categorized as upfront cranial radiation therapy (ucRT group), excluding those treatments performed during prior EGFR-TKI treatment. Overall survival (OS), progression-free survival (PFS), and the time to intracranial progression (iTTP) were compared between the 2 groups, with adjustment by covariates in propensity-score matched (PSM) analyses. The state of having 1 to 3 BM lesions, with a maximal size of ≤3 cm, was defined as having oligo-BM; otherwise; the cases were defined as having multiple BMs. Results Of the 205 patients enrolled, osimertinib was used as first-line therapy in 74 and second-line therapy in 131. There were 48 patients who received ucRTs, including WBRT in 24 and SRS in 24. All patients with oligo-BM in the ucRT group received SRS alone (n = 17), whereas most (n = 28; 90.3%) patients with multiple BMs received WBRT. Failure pattern analyses indicated that in the non-ucRT group, 40.2% of the initial PD involved the brain and 76.9% of the cranial PD involved the original sites, indicating the potential roles of ucRT. Indeed, the iTTP was significantly prolonged (P = .010) in the ucRT group among the whole population. In the PSM oligo-BM cohort, the ucRT group showed superior PFS (P = .033) and OS (P = .026) compared with the non-ucRT group, and the differences remained after multivariate Cox analyses. No such differences were observed in the subpopulation with multiple BMs. Conclusions In osimertinib-treated NSCLC patients with BMs, oligo-BM status could be used as a potential factor to select patients for upfront cranial RT. Further investigation by well-designed clinical trials is warranted.