Volumetric modulated arc therapy for early-stage gastric mucosa-associated lymphoid tissue lymphoma

초록

Purpose/Objective: To investigate clinical outcomes and normal organ sparing of volumetric modulated arc therapy (VMAT) for earlystage gastric mucosa-associated lymphoid tissue (MALT) lymphoma Material/Methods: A retrospective analysis of 27 patients with early-stage gastric MALT lymphoma treated with radiation therapy (RT) between January 2016 and December 2022 was conducted. RT was indicated for patients with Helicobacter pylorinegative gastric MALT lymphoma or those who failed to achieve complete remission after Helicobacter pylori eradication. All patients were treated with involved-site radiation therapy with 30 Gy in 20 daily fractions. Imageguided RT with daily cone-beam computed tomography scans was performed. Complete remission rate, recurrence rate, overall survival, and disease-specific survival were evaluated. To compare the normal organ sparing of VMAT plans with three-dimensional conformal RT (3D-CRT) plans, the mean dose (Dmean) and volume of each organ that received x Gy (Vx) were calculated. Acute and chronic complications were assessed according to the Radiation Therapy Oncology Group and the European Organization for Research and Treatment of Cancer toxicity criteria. Results: The median follow-up duration was 18.6 (range, 7.7–80.5) months. All patients were diagnosed with stage I gastric MALT lymphoma. Complete remission was achieved in all patients at a median of 1.6 (range, 0.1–7.4) months postRT. No patients developed local or distant recurrence. All patients achieved survival except one who died of pancreatic adenocarcinoma 43.8 months after RT completion. The 5-year overall survival and disease-specific survival rates were 75% and 100%, respectively. No instances of grade ≥3 acute and late toxicities were identified. In the analysis of dose-volumetric parameters for organs at risk, the Dmean, V10, and V20 for the liver were lower in the VMAT plans than in the 3D-CRT plans (11.9 ± 2.2 Gy vs. 14.2 ± 3.6 Gy, p < 0.05; 47.8 ± 14.8% vs. 64.3 ± 20.7%, p < 0.05; 15.7 ± 6.1% vs. 22.5 ± 9.6%, p < 0.05). The right kidney had lower V20 in the VMAT plans compared to that in the 3D-CRT plans, without significant difference (0.3 ± 1.2% vs. 3.4 ± 5.4%, p = 0.072). The conformity index values for the VMAT plans and the 3D-CRT plans were 1.14 ± 0.03 and 2.40 ± 0.90, respectively (p < 0.05). Conclusion: RT can achieve excellent outcomes in patients with early-stage gastric MALT lymphoma with minimal toxicity. VMAT provides better organ sparing than 3D-CRT.