RADT-28. THE ROLE OF CRANIAL RE-IRRADIATION IN EGFR MUTANT LUNG CANCER PATIENTS WITH BRAIN METASTASES

Abstract INTRODUCTION Re-irradiation with stereotactic radiosurgery (SRS) or whole-brain radiotherapy (WBRT) may be used for treating recurrent brain metastases. Here, we are reporting on the rate of cranial re-irradiation based on our institutional experience in patients with mutated Epidermal Growth Factor Receptor Non-Small Cell Lung Cancer (mEGFR-NSCLC). METHODS This is a retrospective review of patients from three NYP-WCM hospitals with brain metastases treated with radiotherapy and Tyrosine Kinase Inhibitors (TKIs) from December 2012 to May 2023. RESULTS Ninety-eight patients (60.5%) out of 162 with brain metastases from mEGFR-NSCLC were treated with radiation. Twenty-seven patients (27.5%) were treated with WBRT. Among 71 patients treated with SRS, 10 (14.1%) patients underwent surgical resection of the dominant brain lesion followed by fractioned SRS (FSRS) to the surgical bed. Sixty-one (85.9%) patients received SRS for intact brain lesions ranging from single fraction 16-20Gy to FSRT with 24Gy –30Gy in 3-5 fractions based on the size and eloquence of the brain site of the brain metastasis. In the SRS group, fifteen (21.1%) patients required at least one more course of cranial irradiation. The mean duration of local intracranial control between the first and the second course of radiation was 19.6 months [range from 2.0- 56.7 months], while from the start of TKI to the first intracranial failure was 11.3 months [0.8m-45.3 months]. In the WBRT group, two patients (7.4%) were treated with another course of WBRT 20Gy in 5 fractions. These two patients started TKI simultaneously with their first course of WBRT; the mean duration of intracranial local control was 12.8 months [range from 11.6-14.1 months]. Both patients suffered significant cognitive declines. CONCLUSION In the Tyrosine Kinase Inhibitor era, patients with brain metastases from mEGFR-NSCLC have protracted progression-free survival. Multiple courses of cranial re-irradiation may be needed. Stereotactic radiotherapy should be preferred for the best results in preserving cognitive functions.