Radiation therapy for gastric mucosa-associated lymphoid tissue lymphoma: dose-volumetric analysis and its clinical implications
PURPOSE Mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach (MLS) has recently been defined as a distinct clinicopathologic entity, often associated with Helicobacter pylori infection. Many regard antibiotic therapy as the primary treatment of MLS, but in the absence of H pylori infection, or when salvage of antibiotic failures is required, gastrectomy and/or chemotherapy have frequently been used. This study evaluates the efficacy of low-dose radiotherapy alone as an alternative to surgery. PATIENTS AND METHODS Seventeen patients with stage I to II(2) low-grade MLS without evidence of H pylori infection or with persistent lymphoma after antibiotic therapy of associated H pylori infection were included in this series. Median age was 69 years (range, 39 to 84). Median total radiation dose was 30 Gy (range, 28.5 to 43.5 Gy) delivered in 1.5-Gy fractions within 4 weeks to the stomach and adjacent lymph nodes. Following treatment, all patients underwent endoscopic evaluation and biopsy at a median of 4 months, at 6-month intervals to 2 years, and annually thereafter. RESULTS All obtained a biopsy-confirmed complete response. At a median follow-up time of 27 months (range, 11 to 68) from completion of radiotherapy, event-free survival was 100%. Treatment was well tolerated, with no significant acute side effects. All remained asymptomatic at last follow-up. CONCLUSION These results suggest that effective treatment of MLS with low-dose radiation therapy alone is feasible and safe, and allows stomach preservation. Longer follow-up evaluation is required to determine the long-term efficacy of this treatment approach and its side effects. Further studies should clarify the indications for radiotherapy in H pylori-negative or antibiotic-resistant cases of MLS.