Craniospinal irradiation prior to stem cell transplant for hematologic malignancies with CNS involvement: Effectiveness and toxicity after photon or proton treatment

Publication date: Available online 10 May 2017
Source:Practical Radiation Oncology
Author(s): Jillian R. Gunther, Ahmad R. Rahman, Wenli Dong, Zeinab Abou Yehia, Partow Kebriaei, Gabriela Rondon, Chelsea C. Pinnix, Sarah A. Milgrom, Pamela K. Allen, Bouthaina S. Dabaja, Grace L. Smith
Purpose/Objective(s)Craniospinal irradiation (CSI) improves local control of leukemia/lymphoma with CNS involvement. However, for adult patients anticipating stem cell transplant (SCT), cumulative treatment toxicity is a major concern. We evaluated toxicities and outcomes for patients receiving proton or photon CSI prior to SCT.Materials/MethodsWe identified 37 consecutive leukemia/lymphoma patients with CNS involvement who received CSI prior to SCT at our institution. Photon vs. proton toxicities during CSI, transplant, and through 100days post-transplant were compared using Fisher's exact and Wilcoxon rank sum tests. Long-term neurotoxicity, disease response, and overall survival were analyzed.ResultsThirty-seven patients (23 photon, 14 proton) underwent CSI for CNS involvement of ALL (49%), AML (22%), CLL (3%), CML (14%), lymphoma (11%) and myeloma (3%). CSI was used for consolidation (30 patients, 81%) and gross disease treatment (7 patients, 19%). Median radiation dose (interquartile range (IQR)) was 24Gy (23.4–24) for photons and 21.8Gy (21.3–23.6) for protons (p=0.03). Proton CSI was associated with lower rates of RTOG Grade 1–3 mucositis during CSI (7% vs. 44%, p=0.03): 1 Grade 3 with protons vs. 5 Grade 1, 3 Grade 2, and 2 Grade 3 with photons. During CSI, other toxicities (infection, GI) did not differ.Allogeneic SCT was used in 95% of patients, with 53% of patients in remission before SCT. Myeloablative conditioning was used for 76%. During SCT admission and 100days post-SCT, toxicities did not differ by CSI technique. Successful engraftment occurred in 95% of patients (p=0.67). Progression or death occurred for 47% of patients, with only one CNS relapse.ConclusionIn our cohort, CSI offered excellent local control for CNS-involved hematologic malignancies in the pre-SCT setting. Acute mucositis occurred less frequently acutely with proton CSI with comparable peri-transplant/long-term toxicity profile, suggesting the need to further explore the benefit/toxicity profile of this technique.



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