Gamma knife radiosurgery for primary CNS lymphoma is an ideal complementary therapy

Christopher Duma1, Peter Chen2, Brian Kim2, Maryann Plunkett2, Ralph Mackintosh2, Ryan Casserly2, Robert Dilman2, Ramin Azhir2, Brittany Whitely2, Alexa Reeves3

1Newport Beach, United States 2Hoag Memorial Hospital, Newport Beach, California, USA 3University of California Irvine, Irvine, California, USA

Keywords: gamma knife, radiosurgery, lymphoma, brain tumor, outcome

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     Standard therapy for primary CNS lymphoma (PCNSL) currently includes high-dose methotrexate-based chemotherapy and whole brain radiation therapy (WBRT), but this approach is associated with significant toxicity, especially neurotoxicity in elderly patients (>age 60 years), who have a median survival of less than 30 months. For this reason WBRT is increasingly reserved for patients less than 60 years of age, and older patients are treated with chemotherapy alone. Gamma Knife radiosurgery (GKRS) has not been widely used in the management of PCNSL because of the belief that PCNSL is a multifocal disease. However, GKRS delivers a localized treatment that should minimize neurotoxicity, potentially produce better local disease control, and possibly lead to better survival rates than approaches that utilize no RT or WBRT.
     The purpose of this report was to evaluate radiosurgery outcomes.
     Between October 2003 and May 2010 ten PCNSL patients, aged 60 to 84 years, were treated with GKRS.
      Doses ranged from 8 Gy to 18 Gy (median: 12) at the 50% isodose line (range: 45-85; median 50). Eight of the ten patients had failed chemotherapy prior to GKRS; two patients were managed with only biopsy and GKRS. Clinical data was gathered for toxicity, disease control, and survival.
     Side effects attributed to GKRS were minimal; no patients had deterioration in quality of life related to treatment. All treated lesions demonstrated a partial or complete response on magnetic resonance imaging. Only one instance of local recurrence has been observed during 2.5 to 58 months of follow up (median followup time 4 years). Median survival is 42 months from initial diagnosis and 40 months from GKRS.
     This was a retrospective review.
     In patients with PCNSL, GKRS is associated with minimal toxicity and good long-term local disease control. In this small series, median survival was over 33% longer than published figures for similar patients treated with chemotherapy ± WBRT. Encouraging disease control and survival combined with a low incidence of neurotoxicity suggest that GKRS may be a desirable component of multimodality treatment of PCNSL.  
     Randomized trials would be needed to establish GKRS as a component of standard therapy in patients over chemotherapy alone.


Project Roles:

C. Duma (), P. Chen (), B. Kim (), M. Plunkett (), R. Mackintosh (), R. Casserly (), R. Dilman (), R. Azhir (), B. Whitely (), A. Reeves ()