Time to treatment failure and duration of response after CHOP and R-CHOP. (A) TTF after start of therapy for CHOP and R-CHOP. In the R-CHOP arm, only 28 of 223 patients experienced treatment failure compared with 61 of 205 patients in the CHOP arm (P < .001). (B) Duration of response after CHOP and R-CHOP. In patients achieving CR or PR after initial therapy, a significantly lower relapse rate was observed after R-CHOP than after CHOP (P = .001).