title: Who benefits from adjuvant radiation therapy for gastric cancer? A meta-analysis.
abstract: OBJECTIVE
  Large randomized trials have demonstrated significant survival benefits with the use of adjuvant chemotherapy or chemoradiation therapy for gastric cancer. The importance of adjuvant radiation therapy (RT) remains unclear. We performed an up-to-date meta-analysis of randomized trials testing the use of RT for resectable gastric cancer.
  
  
  METHODS
  We searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials for randomized trials testing adjuvant (including neoadjuvant) RT for resectable gastric cancer. Hazard ratios describing the impact of adjuvant RT on overall survival (OS) and disease-free survival (DFS) were extracted directly from the original studies or calculated from survival curves. Pooled estimates were obtained using the inverse variance method. Subgroup analyses were performed to determine whether the efficacy of RT varies with chemotherapy use, RT timing, geographic region, type of nodal dissection performed, or lymph node status.
  
  
  RESULTS
  Thirteen studies met all inclusion criteria and were used for this analysis. Adjuvant RT was associated with a significant improvement in both OS (HR = 0.78, 95% CI: 0.70-0.86, P<.001) and DFS (HR = 0.71, 95% CI: 0.63-0.80, P<.001). In the 5 studies that tested adjuvant chemoradiation therapy against adjuvant chemotherapy, similar effects were seen for OS (HR = 0.83, 95% CI: 0.67-1.03, P=.087) and DFS (HR = 0.77, 95% CI: 0.91-0.65, P=.002). Available data did not reveal any subgroup of patients that does not benefit from adjuvant RT.
  
  
  CONCLUSIONS
  In randomized trials for resectable gastric cancer, adjuvant RT provides an approximately 20% improvement in both DFS and OS. Available data do not reveal a subgroup of patients that does not benefit from adjuvant RT. Further study is required to optimize the implementation of adjuvant RT for gastric cancer with regard to patient selection and integration with systemic therapy.
authors.affiliation: Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York, USA. ohri.nitin@gmail.com
authors.forename: Nitin
authors.initials: N
authors.lastname: Ohri
authors.forename: Madhur K
authors.initials: MK
authors.lastname: Garg
authors.forename: Santiago
authors.initials: S
authors.lastname: Aparo
authors.forename: Andreas
authors.initials: A
authors.lastname: Kaubisch
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Tome
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Kennedy
authors.forename: Shalom
authors.initials: S
authors.lastname: Kalnicki
authors.forename: Chandan
authors.initials: C
authors.lastname: Guha
mesh_terms: D018572:Disease-Free Survival; D006801:Humans; D018714:Radiotherapy, Adjuvant / Q000401:mortality; D016032:Randomized Controlled Trials as Topic; D013274:Stomach Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery