Leukemia/Lymphoma/Hematologic

SS 25 - Hematologic 2 - Translating Better Technology to Reduced Toxicity

182 - Excellent Outcomes After Reduced-Dose Intensity Modulated Radiation Therapy for Gastric Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma

Tuesday, October 23
2:20 PM - 2:30 PM
Location: Room 004

Excellent Outcomes After Reduced-Dose Intensity Modulated Radiation Therapy for Gastric Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma
C. C. Pinnix1, J. R. Gunther1, S. A. Milgrom1, R. J. Cruz Chamorro2, L. J. Medeiros3, J. Khoury4, B. Amini5, M. A. Fanale6, S. S. Neelapu4, H. Lee4, J. Westin4, N. Fowler4, L. Nastoupil4, and B. Dabaja1; 1The University of Texas MD Anderson Cancer Center, Division of Radiation Oncology, Houston, TX, 2Ponce Health Sciences University, Ponce, PR, 3The University of Texas MD Anderson Cancer Center, Department of Hematopathology, Houston, TX, 4University of Texas MD Anderson Cancer Center, Houston, TX, 5Dept. of Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX, 6MD Anderson Cancer Center, Houston, TX

Purpose/Objective(s): Radiation therapy (RT) can be curative for patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma, however the optimal RT dose is not well defined. We sought to report the outcome and patterns of relapse among patients treated definitively with modern RT using standard and reduced RT doses (≥30 Gy vs. 24 Gy).

Materials/Methods: We reviewed the charts of 31 consecutive patients with pathologically confirmed gastric MALT lymphoma diagnosed between 2007 and 2017 and treated with definitive intensity modulated radiation therapy (IMRT) at a single institution. Complete response (CR) to therapy was defined based on post-RT endoscopic biopsy that showed either complete histological response (ChR) or probable minimal residual disease (pMRD), according to GELA (Groupe d’Etude Des Lymphomes de l’Adult) criteria. Clinical and treatment-related factors were analyzed for association with freedom from local failure (FFLF), progression-free survival (PFS), and overall survival (OS).

Results:: The median age at diagnosis was 60 years (range, 32-88 years). 39% (n=12) were female and 81% (n=25) had stage I disease. Regional lymph node involvement was present in 16% (n=5). The MALT-IPI score was 0 in 84% (n=26) and 1 in 16% (n=5). Helicobacter pylori infection was detected in 19% (n=6). Thirty two percent (n=10) of patients had recurrent/residual disease after antibiotic therapy. Systemic therapy with rituximab (n=2) or rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP, n=3) was administered prior to RT; one patient had a CR, 2 had persistent disease and 2 patients did not have a disease assessment after systemic therapy and prior to RT. One patient received concurrent rituximab. Gross disease was documented just prior to RT in 90% (n=28) of patients. RT was administered with IMRT in all patients. The median dose was 30 Gy (range 24-36 Gy); 7% received 36 Gy (n=2), 58% received 30 Gy (n=18) and 36% received 24 Gy (n=11). Post-RT biopsy revealed ChR in 97% (n=30) and pMRD in 3% (n=1). One local failure occurred in the stomach 67 months after completion of 30 Gy. Two patients experienced extra-gastric failures in the duodenum and lungs, 56 and 23 months respectively, after 30 Gy. At a median follow up time of 56 months (95% CI 30 - 83 months) for the entire cohort, the 5-year FFLF, PFS and OS were 100%, 87% and 97%, respectively. The median follow up for patients treated with doses ≥ 30 Gy was 61 months (95% CI 68 - 84 months) compared to 31 months (95% CI 25 - 37 months) for patients treated with a dose of 24 Gy (p<.001). There was no association between a dose of 24 Gy with FFLF (p=1), PFS (p=.31) or OS (p=.46).

Conclusion: RT is associated with excellent CR rates for patients with gastric MALT lymphoma, even with reduced doses of 24 Gy. Additional follow up is required to determine if long-term local control and cure can be achieved with lower RT doses.

Author Disclosure: C.C. Pinnix: None. J.R. Gunther: None. R.J. Cruz Chamorro: None. L.J. Medeiros: None. J. Khoury: None. B. Amini: None. H. Lee: None.

Chelsea Pinnix, MD, PhD

MD Anderson Cancer Center

Disclosure:
Employment
MD Anderson Cancer Center: Assistant Professor: Employee

Compensation
Global Oncology One: Consultant; Merck & Co.: Research Grants

Leadership
International Journal of Radiation Oncology, Biology and Physics: Senior Editor

Presentation(s):

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