T. Veeramachaneni1, B. Tortelli2, X. D. Li2, N. B. Desai2, H. Wolfe3, E. Yilmaz3, F. Awan3, R. Collins4, R. D. Timmerman5, P. Ramakrishnan Geethakumari3,6, M. Korzak4, and K. A. Kumar Jr2; 1UT Southwestern Medical School, Dallas, TX, United States, 2Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, 3Department of Hematology and Oncology, University of Texas Southwestern Medical Center, Dallas, TX, 4University of Texas Southwestern Medical Center, Dallas, TX, 5Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX, 6Division of Hematologic Malignancies and Stem Cell Transplantation, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX
Purpose/Objective(s):Recommendations for hypofractionated courses (5-13 fractions) of ISRT in lymphomas arose during the time of COVID-19 (Yahalom et al Blood 2020) as modern radiation techniques should allow similar total doses to be delivered safely in far fewer fractions. Our aim is to evaluate the outcomes and toxicities of ultra-hypofractionated (</=5 fractions) ’definitive’ intent ISRT in aggressivechemorefractorynon-Hodgkin lymphomas (nHL) to see if this may be an acceptable alternate recommendation when shorter treatment time is desired.Materials/
Methods: We conducted an IRB-approved, retrospective review of all aggressive nHL patients treated at our institution with definitive intent (40-50 Gy EQD2 with an a/ß of 10) ultra-hypofractionatedISRT between April 2020 and July 2023. Demographic, disease-specific, and treatment-related variables were collected. Primary outcomes include objective response rate (ORR), defined as complete (CR) or partial response (PR) on post-RT PET scans using the Lugano classification, local failure (LF), and radiation-related toxicity per CTCAE v5. Secondary outcomes include overall disease control and survival. Results: 30 ultra-hypofractionated radiation treatments were identified from 27 unique patients who were treated with definitive intent ISRT (33.3% salvage, 37.0% early-salvage post CAR-T, and 29.6% bridging to SCT or CAR-T). The most common dose was 30 Gy in 5 fractions (97%); all patients were treated with IMRT with SBRT-type immobilization and image guidance as indicated. The most common diagnosis was DLBCL (89%). 12/27 (52%) patients were female, the majority (85%) were ECOG 0-1 performance status, and the average age at time of RT was 67.3 years. 37% had all FDG-avid sites at the time of radiation treated. Median follow-up was 7.2 months (IQR 12.1 months). 30% of patients had acute radiation related toxicities, most commonly fatigue (50%). All toxicities were grade, and there were no subacute or long-term toxicities. Initial local ORR was 25/26, or 96% (85% CR and 12% PR), while initial overall ORR was 15/26, or 58% (56% CR and 4% PR). At time of last follow up, only 1/26 (4%) of irradiated sites had local failure (1 data point N/A), with a TTLF of 1.5 months. 62% of patients had disease progression (DP), with median time to DP of 1.5 months. At time of last follow up, 41% were dead, with a median time to death of 6.6 months. Conclusion: Ultra-hypofractionated ISRT in the ‘definitive’ intent treatment of aggressive non-Hodgkin lymphomas has excellent local tumor control and appears to be safe with minimal acute and subacute toxicities. In addition to patient convenience and cost effectiveness, short-course ISRT allows patients to quickly move on to next-line therapy when indicated. Prospective studies and long-term follow up are needed to further validate this as an alternative radiation treatment option.
