3378 - The Impact of Radiotherapy on Survival Outcomes in Plasmablastic Lymphoma

P. A. Haddad¹, J. L. Lerner², and S. Gupta²; ¹LSUHSC-S/Overton Brooks VAMC, Shreveport, LA, ²LSUHSC-S/Feist-Weiller Cancer Center, Shreveport, LA

Purpose/Objective(s): Plasmablastic Lymphoma (PBL) is a rare and aggressive subtype of non-Hodgkin’s lymphoma. It is often associated with immunosuppressive clinical contexts, such as HIV infection and immunosuppressive therapies for autoimmune disorders and organ transplants. However, due to the rarity of the disease, which is poorly understood, varied treatment approaches have been implemented, and no optimal data or guidelines for managing PBL are available. Therefore, we conducted this pooled database analysis to identify the impact of radiotherapy (RT) on survival outcomes in this rare disease. Materials/

Methods:

To study the demographic characteristics, molecular and immunohistochemical signatures, therapeutic interventions, survival, and prognostic factors, we compiled a pooled database of cases that fit the diagnostic criteria for PBL. Kaplan-Meier survival curves were constructed. Cox proportional hazards model and Log-rank tests were used to assess the influence of demographic and clinicopathologic factors on overall survival (OS).
Results:

A total of 300 patients with confirmed PBL were identified. The median age was 49. There was a male preponderance (M:F 2.7). Stage III/IV accounted for 51% of the cohort. Sixty-two percent were immunosuppressed, 47% due to HIV. The median OS and DFS of the whole group were 25 and 15 months, respectively. The involvement of BM (p<0.0001), liver (p=0.003), lungs/pleura (p<0.0001), and upper GI tract (0.001) was associated with worse OS. Meanwhile, stage<2 (p<0.0001) and involvement of the head and neck (H&N) (p=0.0001) had better OS. Compared to no treatment, chemotherapy (CT) and stem cell transplant had incrementally superior median OS (2 vs. 27 vs. NR months, p<0.0001). Frontline intensive CT yielded better OS than CHOP-like and myeloma regimens in decreasing order (p<0.0001). Patients who attained CR as their best response also had a superior median OS (p<0.0001). Patients who received RT had better OS (p=0.004). When analyzed by stage, RT mainly impacted early stages (I&II) (NR vs. 27mo). RT improved OS when added to intensive and non-intensive CT (p=0.03), particularly in the early stages (p=0.0002). When analyzed by anatomic area, RT’s OS impact was restricted to H&N (p=0.0008).
Conclusion: This study represents a large, pooled cohort of patients with PBL. It supports a chemoradiotherapy approach for early-stage PBL, particularly in the H&N area, as the most optimal approach to optimize OS.