title: Radiation therapy for gastric mucosa-associated lymphoid tissue lymphoma: dose-volumetric analysis and its clinical implications.
abstract: OBJECTIVE
  To assess the clinical outcomes of radiotherapy (RT) using two-dimensional (2D) and three-dimensional conformal RT (3D-CRT) for patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma to evaluate the effectiveness of involved field RT with moderate-dose and to evaluate the benefit of 3D-CRT comparing with 2D-RT.
  
  
  METHODS
  Between July 2003 and March 2015, 33 patients with stage IE and IIE gastric MALT lymphoma received RT were analyzed. Of 33 patients, 17 patients (51.5%) wereHelicobacter pylori(HP) negative and 16 patients (48.5%) were HP positive but refractory to HP eradication (HPE). The 2D-RT (n = 14) and 3D-CRT (n = 19) were performed and total dose was 30.6 Gy/17 fractions. Of 11 patients who RT planning data were available, dose-volumetric parameters between 2D-RT and 3D-CRT plans was compared.
  
  
  RESULTS
  All patients reached complete remission (CR) eventually and median time to CR was 3 months (range, 1 to 15 months). No local relapse occurred and one patient died with second primary malignancy. Tumor response, survival, and toxicity were not significantly different between 2D-RT and 3D-CRT (p > 0.05, each). In analysis for dose-volumetric parameters, Dmaxand CI for PTV were significantly lower in 3D-CRT plans than 2D-RT plans (p < 0.05, each) and Dmeanand V15for right kidney and Dmeanfor left kidney were significantly lower in 3D-CRT than 2D-RT (p < 0.05, each).
  
  
  CONCLUSIONS
  Our data suggested that involved field RT with moderate-dose for gastric MALT lymphoma could be promising and 3D-CRT could be considered to improve the target coverage and reduce radiation dose to the both kidneys.
authors.affiliation: Proton Therapy Center, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Hyeon Woo
authors.initials: HW
authors.lastname: Lim
authors.affiliation: Proton Therapy Center, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Center for Gastric Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Il Ju
authors.initials: IJ
authors.lastname: Choi
authors.affiliation: Center for Gastric Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Chan Gyoo
authors.initials: CG
authors.lastname: Kim
authors.affiliation: Center for Gastric Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Jong Yeul
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Center for Gastric Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Soo Jeong
authors.initials: SJ
authors.lastname: Cho
authors.affiliation: Center for Specific Organs Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Hyeon Seok
authors.initials: HS
authors.lastname: Eom
authors.affiliation: Proton Therapy Center, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Moon
authors.affiliation: Proton Therapy Center, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Dae Yong
authors.initials: DY
authors.lastname: Kim
keywords: Lymphoma; Radiotherapy; Stomach