Whole Brain Radiation or Fractionated Stereotactic Radiosurgery For Brain Metastases With or Without Immunotherapy or Targeted Therapy.

Summary: There is limited data on the safety of immunotherapy (IT) or targeted therapy (TT) given concurrently with radiation (XRT) to the Central Nervous System (CNS). We present our experience on patients with CNS metastases treated with whole brain radiation (WBRT) or stereotactic radiosurgery (SRS) with or without IT or TT. We performed a retrospective review of all patients who underwent radiation to the brain for CNS metastases with or without TT or IT. From January 2015 to July 2022, 38 patients with CNS metastasis were treated with either WBRT or SRS. WBRT was delivered to 40 Gy in 20 treatments and was the preferred treatment in patients with 4 or more CNS metastases. SRS dose was to 25 Gy in 5 fractions and was the preferred treatment in patients with 3 or less CNS metastases. Both treatments used face mask immobilization. Decisions to treat with concurrent IT or TT was made according to medical oncologist preference. Patients were followed every three months after completion of WBRT or SRS. MRI brain scans were obtained at each follow up to asses for recurrences. Other scans such as PET/CT scans were obtained as indicated. Meean follow up was 90 months. 20 patients were treated with XRT alone. 15 patients underwent SRS treatment and 18 patients were treated with WBRT. 5 patients received both WBRT and SRS as a boost. 8 patients were treated concurrently with IT. 7 patients were treated with TT depending on the molecular profile. 3 patients were treated with both IT and TT. Median survival for patients treated with XRT alone or with concurrent IT/TT with XRT was 5.48 and 12.16 months respectively (p=0.04). No excess rates of radionecrosis were noted. No excess rate of acute or late toxicities were noted. Although out study was limited, our data suggests that concurrent use of TT or IT during WBRT or SRS is feasible without an increased amount of toxicity. Further studies are warranted. morteza dowlatshahi (he/him/his), MD DABR FACRO (Presenting Author) - Cancer Care Institute; Ly Do, MD (Co-Author) - Cancer Care Institute; Raymond Lee, MD (Co-Author) - Evergreen Hematology Oncology Associates; Charlene Lee, MD (Co-Author) - Evergreen Hematology Oncology Associates; Tin Hla, MD (Co-Author) - Cancer Care Institute; Ryan Ghiassi, BS (Co-Author) - Cancer Care Institute