Duration of response for patients receiving IFN-α maintenance therapy or undergoing peripheral blood stem cell transplantation after CHOP and R-CHOP. Median duration of response has not been reached in patients receiving IFN-α maintenance after R-CHOP therapy, whereas it was 26 months after CHOP therapy (P = .001). At the time of this analysis, no differences were observed in patients after initial therapy with R-CHOP or CHOP who subsequently underwent intensification therapy followed by myeloablative radiochemotherapy and peripheral blood stem cell transplantation (PBCT).