Summary of the eligible studies in this meta-analysis.

NHL = non-Hodgkin lymphoma; HD = Hodgkin lymphoma or Hodgkin disease; NK/TCL = natural killer cell and T cell lymphoma; DLBCL = diffuse large B cell lymphoma; IHC = immunohistochemistry; qPCR = quantitative real-time polymerase chain reaction; OS = overall survival curve; RP = HR reported directly; HR = hazard ratios; NA = not available. Study quality is listed using the results of the Newcastle -Ottawa questionnaire (Table 1). Summary results were either positive (95% CI above 1.0) or negative (95% CI below 1.0) or indeterminate (95% CI crossing 1.0).