Craniospinal Irradiation (CSI) in Acute Lymphoblastic Leukemia: Comparison between Conformal Radiotherapy, Intensity-Modulated Radiotherapy, and Helical Tomotherapy (HT)

Abstract

Purpose: According to preliminary clinical experience, craniospinal irradiation (CSI) may be considered as a treatment option in patients with recurrent leukemia involving the central nervous system (CNS). Field matching poses challenges as it leads to a risk of underdosage or overdosage in the junctional area. We investigated the feasibility of CSI using helical tomotherapy (HT). Patients and methods: Four patients presenting with CNS recurrences of leukemia were referred to our department for salvage radiation therapy. Treatment planning was conducted by the EclipseTM system for 3D-CRT and IMRT, and with the Tomotherapy ® software for HT. Acute adverse events were monitored weekly using the Common Terminology Criteria for Adverse Events v 4.0. Results: Using HT, highly conformal irradiation could be delivered to CNS. Average doses to the encephalon were 25.1 Gy, 15.5 Gy, and 23.3 Gy using 3D-CRT, IMRT, and HT respectively. Spinal cord received an average dose of 18.9 Gy with 3D-CRT, 15.7 Gy with IMRT and 23.4 Gy with HT. Areas of overdosage to the brain or the spinal cord were also significantly decreased with HT. With HT, average doses to critical organs were also significantly decreased. No acute toxicity was reported with HT, whereas the patients treated by 3D-CRT and IMRT presented with grade II vomiting and asthenia. Conclusion: HT may optimize CSI in the treatment of CNS hematological recurrences by homogenously covering target volumes and improve clinical acute tolerance by more effectively sparing critical organs for preserving the quality of life. Further prospective assessments are warranted.