Treatment failure rates according to risk groups. (A) current study, (B) prior multicenter prospective trial. Standard risk, 0 to 2 risk factors; high risk, 3 to 4 risk factors. Risk factors included time interval <12 months from transplantation to initial treatment, patient age ≥60 years, severe involvement (score 3) of the gastrointestinal tract, liver, or lungs, and Karnofsky score <80% at initial treatment. Results for the high-risk group were not plotted in B, because only 2 patients were included in this group. These 2 patients had early treatment failure at 15 and 19 days after initial treatment, respectively.