Abstract Details

To assess the benefit and toxicity of whole brain RT (WBRT), WBRT with conformal boost, and conformal RT, with or without concurrent temozolomide (TMZ), for CNS lymphoma.

WBRT to 45Gy for CNS lymphoma has been shown to have undesirable amounts of neurocognitive toxicity. Radiation is presently used mainly for persistent or recurrent disease, but the optimal regimen has not been defined. 

This is a single-center retrospective study of adult patients treated with RT between 01/2004-02/2019 for CNS lymphoma, with a treatment plan formulated at our institution with ≥1 follow-up. Overall survival (OS) was analyzed by Kaplan-Meier, multivariate analysis was performed, and toxicity was assessed using CTCAEv5.0.  Long-term neurocognitive impacts were assessed at last follow-up.

93 patients were included, with median age of 60, 45% female, and 73% with primary CNS lymphoma. Radiation modalities included low-dose (≤23.4Gy) WBRT (n=19), high-dose WBRT (n=27), low-dose WBRT + focal boost (n=38) and focal RT (n=9). Twenty-six patients (28%) received concurrent RT+TMZ. Two-year OS was better with low-dose WBRT+boost (60%) compared to low-dose WBRT (45%) or high-dose WBRT (32%). Two-year OS was significantly better with RT+TMZ than RT alone (67% vs 42%, p=0.025). On multivariate analysis, low-dose WBRT+boost+TMZ was significantly associated with improved OS compared to WBRT alone (HR 0.35, p=0.02). Within two months of RT completion, one patient developed grade 3+ hematologic toxicity in both the TMZ and non-TMZ groups; 4 and 5 patients, respectively, developed grade 3+ non-hematologic toxicity. Less than 25% of the patients in each group experienced long-term neurocognitive decline at last follow-up.

A regimen of low-dose WBRT with focal boost and the addition of concurrent temozolomide were both associated with improved OS in CNS lymphoma patients, with similar toxicity rates. Radiation regimens with most or all of the brain receiving ≤23.4Gy were associated with fairly low rates of cognitive decline.