Involved-site radiotherapy for Helicobacter pylori-independent gastric MALT lymphoma: 26 years of experience with 178 patients

Abstract

Treatment options for Helicobacter pylori-independent gastric mucosa-associated lymphoid tissue (MALT) lymphoma (GML) include surgery, immunotherapy, chemotherapy, and radiation therapy (RT). The purpose of this study was to investigate the efficacy and safety of RT and routine endoscopic surveillance, hypothesizing that most patients are curable with RT alone. We queried a single institution database at a tertiary referral cancer center for patients with H pylori-independent GML treated with RT between 1991 and 2017. Response was assessed by follow-up endoscopies (EGDs) starting 10 to 12 weeks post-RT. Computed tomography scans were also part of the follow-up program, and positron emission tomography was added when clinically appropriate. We identified 178 patients (median age, 63 years; range, 25-89 years); 86% had stage I disease, 7% had stage II disease, and 7% had stage IV disease. Median RT dose was 3000 cGy over 20 fractions. Ninety-five percent of patients exhibited complete pathologic response on posttreatment EGD. Two patients experienced grade 3 toxicity, and 2 patients experienced in-field secondary malignancies. Over a median follow-up of 6.2 years, 9.6% experienced local failures, and 11.8% developed distant sites of disease. Five-year and 10-year overall survival were 94% and 79%, respectively, from last date of RT. RT is a highly effective and safe treatment for GML with excellent overall survival and very rare acute or late treatment-related toxicities. Favorable outcomes from this large retrospective sample of patients provide credible and compelling support for RT as standard of care for H pylori-independent GML.

Graphical abstract

Figure 1.

OS and PFS. Kaplan-Meier analysis of OS (upper panel) and PFS (lower panel). OS was defined as survival from all causes and was calculated from date of last RT. End points for PFS included death from any cause, local failure, and distant disease failure. Survivors were followed for a median of 6.2 years (range, 1.6-22.8). Median OS was 16.5 years. Five-year and 10-year OS estimates were 94% and 79%, respectively. Presenting stage was highly significant for PFS (P < .001), local failure (P < .001), and distant failure (P = .003).

Figure 2.

EGD images documenting pathologic complete response. EGD images from patient 6, whose experienced spontaneous normalization without salvage treatment.

Figure 3.

Natural history of EGD abnormalities. Fifteen patients who presented with early-stage GML exhibited residual GML on posttreatment EGD biopsy. Pathology review reported no evidence of disease (green circle), atypical lymphoid cells (blue circle), or residual GML (red open circle). Five patients with atypical lymphoid cells subsequently progressed to local failure (patients 2, 3, 4, 5, and 9). Three patients (6, 8, and 14) had pathologic EGD failures that self-resolved with observation alone.

Figure 4.

Local and distant disease failures. Cumulative incidence of local and distant failures for patients treated for early-stage GML (N = 166), using death as a competing risk. Five-year and 10-year local failure rates were 3.9% and 8.3%, respectively, whereas 5-year and 10-year distant failure rates were 6.9% and 11%, respectively.