Five-year cumulative incidence of isolated relapse by route of methotrexate (MTX) administration during the interim maintenance phases. Five-year cumulative incidence of isolated CNS relapse (A), isolated testicular relapse (B), and isolated non-CNS nontesticular extramedullary relapse (C) by route of MTX administration during the interim maintenance phases. PO indicates oral; RHR, relative hazard ratio.