ESTRO 2024 - Abstract Book

S1162

Clinical - Haematology

ESTRO 2024

Sung-Hsin Kuo 1,2,3 , Pei-Jun Chen 1 , Ming Yao 4 , Yu-Hsuan Chen 1 , Chiao-Ling Tsai 1 , Keng-Hsueh Lan 1,3 , Chun-Wei Wang 1 , Ann-Lii Cheng 1,5,4 1 National Taiwan University Hospital, Department of Oncology, Taipei, Taiwan. 2 National Taiwan University College of Medicine, Graduate Institute of Oncology, Taipei, Taiwan. 3 National Taiwan University Cancer Center, Department of Radiation Oncology, Taipei, Taiwan. 4 National Taiwan University Hospital, Department of Internal Medicine, Taipei, Taiwan. 5 National Taiwan University Cancer Center, Department of Medical Oncology, Taipei, Taiwan

Purpose/Objective:

In addition to Helicobacter pylori (HP)-positive gastric mucosa-associated lymphoid tissue (MALT) lymphoma, we reported that a proportional of patients with HP-negative gastric MALT lymphoma and with extragastric MALT lymphoma are still responsive to first-line antibiotics treatment [1,2]. However, the optimal management for localized antibiotics-unresponsive MALT lymphoma has yet to be clarified. The purpose of this study was to assess the treatment efficacies, the toxicities, and the clinical outcomes for patients with localized MALT lymphoma undergoing definitive radiotherapy.

Material/Methods:

Patients with localized (modified Ann Arbor stage I and IIE) MALT lymphoma who underwent first-line radiotherapy or radiotherapy after failing to first-line antibiotics treatment between July 1990 and Dec. 2021 were retrospectively reviewed. Patients diagnosed with histologically high-grade transformed MALT lymphoma were excluded. In this study, all radiotherapy techniques were allowed, including two-dimensional radiotherapy (2DRT), electron beam with lens shielding, three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), or tomotherapy. We calculated the event-free survival (EFS) and overall survival (OS) for all patients using the Kaplan-Meier method.

Results:

There were 34 women and 49 men, with a median age of 58 years (range 18-90) were included in this analysis. Among them, 59 (71%) patients had stage IE disease and 24 (29%) patients with stage IIE. The most common primary sites were the ocular adnexal region (38 cases), followed by salivary glands (14 cases), Waldeyer’s ring and neck regions (13 cases), lung (5 cases), stomach (3 cases), and the other regions (10 cases). The median administration of radiotherapy dose was 30.6 Gy (range 24-50), and the median fraction of radiotherapy was 17 (range 10-25). Among our patients, 17 patients underwent 2DRT or electron beam with lens shielding, 23 patients received 3DRT, 20 patients underwent IMRT, and 23 patients underwent VMAT or tomotherapy. Most of the fraction size of radiotherapy was 2 Gy per fraction, whereas the biologically effective dose (alpha/beta ratio = 10) was 37.5 Gy (range 28.8-60). Radiotherapy resulted in an overall response rate of 86.7%: 60 patients achieved complete remission, while 12 patients had partial remission. After a median follow-up of 8.8 years (95% confidence interval [CI], 6.487 to 11.11), the 8-year event-free survival rate and overall survival rate were 81.4% and 88.6%, respectively, for all patients. The most common acute side effects were dermatitis (16 cases presented with grade 1 events, 19.2%), whereas the second common acute reaction was mucositis (10 cases with grade 1 to 2 events). Among patients with ocular adnexal MALT lymphoma, cataract was the most common late ophthalmological complication, occurring in 8 patients.