Main Session
Sep
28
PQA 04 - Breast Cancer, Patient Reported Outcomes/QoL/Survivorship, Functional Radiation Medicine, Hematologic Malignancies, Palliative Care, and International/Global Oncology
2853 - Outcomes of Focal Radiation Therapy in the Treatment of Primary and Secondary Central Nervous System Lymphoma
Presenter(s)
Ellen Ruan, BS - Midwestern University, AZCOM, Glendale, AZ
E. Ruan1, W. Breen2, M. M. Voss3, Y. Bai4, S. C. Lester2, W. G. Rule5, J. L. Peterson6, B. S. Hoppe7, and R. Tao5; 1Midwestern University, AZCOM, Glendale, AZ, 2Department of Radiation Oncology, Mayo Clinic, Rochester, MN, 3Department of Quantitative Health Sciences, Mayo Clinic, Phoenix, AZ, 4Department of Radiation Oncology, Mayo Clinic AZ, Phoenix, AZ, 5Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 6Department of Radiation Oncology, Mayo Clinic, Jacksonville, FL, 7Mayo Clinic, Department of Radiation Oncology, Jacksonville, FL
Purpose/Objective(s):
Primary and secondary central nervous system lymphomas (CNSL) are aggressive malignancies traditionally treated with high-dose methotrexate-based chemotherapy followed by whole-brain radiation therapy (WBRT) for consolidation or salvage therapy. Focal approaches such as stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) have emerged as potential alternatives that may provide effective local tumor control while minimizing radiation exposure to the uninvolved brain parenchyma. We sought to evaluate treatment response, patterns of failure, and survival outcomes in patients with CNS lymphoma treated with SRS/SRT.Materials/Methods:
This was a retrospective analysis of patients with primary or secondary CNS lymphoma treated with SRS/SRT at 3 institutions from 2017-2025. Overall survival (OS) and recurrence-free survival (RFS) were estimated using the Kaplan-Meier method. Patterns of failure were evaluated with local recurrence, out-of-field brain recurrence, and extracranial distant recurrence. Univariate Cox proportional hazards regression was performed to identify factors associated with survival and recurrence outcomes.Results:
We identified 38 patients with a median age of 68 years (range 37-83); 42% of patients were female. The majority of patients received systemic therapy (31/38, 82%), 10 patients (26%) received an autologous stem cell transplant, and only 1 patient (2.6%) received WBRT prior to SRS/SRT. Eight patients (21%) received CAR-T therapy (4 patients prior to RT and 4 after RT). The median RT dose was 25 Gy (IQR 19.5-25 Gy) given in 5 fractions (IQR 2-5). The median follow-up was 11.3 months (IQR 4.5-21 months). Fifteen patients (40%) remained alive at the time of last follow-up. Median OS was 1.7 years after RT. The 1-year OS was 63%, 2-year OS was 43%, and 5-year OS was 16%. A total of 21 patients (55%) experienced disease recurrence at a median time of 1.2 years after RT. The 1-year RFS was 51%, 2-year RFS was 37%, and 5-year RFS was 12%. The predominant pattern of failure was out-of-field brain recurrence (45%) followed by local recurrence (26%) and extracranial distant recurrence (5%). Median time to out-of-field brain recurrence was 1.4 years. Nine patients (24% of all patients, 53% of those with recurrent disease in the brain) were treated with additional course(s) of RT. The RT dose was not associated with local recurrence, but increasing the number of fractions was associated with an higher risk of local recurrence (HR 1.135; 95% CI,1.005-1.282; p=0.041).Conclusion:
We observed promising rates of OS and RFS in patients with CNS lymphoma treated with SRS/SRT. Although out-of-field brain recurrences remain a challenge, about half of the patients could be treated with additional course(s) of RT. We observed a local recurrence rate that was higher than what is reported in the literature after SRS and found that more fractionated radiation treatments were associated with a higher risk of local recurrence.