Reduced-dose Radiation Therapy for Stage IE Gastric Mucosa-Associated Lymphoid Tissue Lymphoma: A Multi-Institutional Prospective Study (KROG 16-18).

PURPOSE

Definitive radiation therapy (RT) of 30 Gy or higher is commonly recommended to treat Helicobacter pylori-independent gastric mucosa-associated lymphoid tissue (MALT) lymphoma with an excellent disease control rate. However, the efficacy of reduced-dose RT has not yet been evaluated in a prospective cohort study. This multi-institutional study aimed to determine the role of reduced-dose RT in the treatment of stage IE gastric MALT lymphoma.

METHODS AND MATERIALS

Between March 2017 and June 2022, 62 patients with histologically confirmed stage IE gastric MALT lymphoma without evidence of H pylori infection were enrolled. The patients were treated with reduced-dose RT at a total dose of 24 to 25.5 Gy to the entire stomach. The response to therapy was evaluated by endoscopy with a biopsy of suspicious lesions if necessary. The primary endpoints were 6-month complete remission (CR) and local failure-free survival.

RESULTS

Among 62 patients, 32 (51.6%) were previously treated for H pylori eradication. Radiation therapy was delivered using 3D-conformal (n = 20, 32.3%) or intensity modulated radiation therapy (n = 42, 67.7%). The median follow-up duration was 34.5 months (range, 9.6-68.8 months). The 6-month CR rate was 96.7%. The 5-year local failure-free survival and progression-free survival rates were 92.0% and 90.4%, respectively. None of the patients experienced grade 3 or worse acute toxicities, and grade 2 acute toxicities were reported in 17 patients (27.4%).

CONCLUSIONS

Reduced-dose RT exhibited excellent response rates in stage IE gastric MALT lymphoma, comparable to historical controls of standard-dose (≥30 Gy) radiation therapy, with a minimal toxicity profile. Current prospective evidence strongly supports the use of definitive radiation therapy (24-25.5 Gy) for the treatment of H pylori-independent stage IE gastric MALT lymphoma.