- Arm II (R-CHOP-21 and radiotherapy): Patients receive R-CHOP as in arm I. Treatment repeats every 21 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. Beginning 2-6 weeks after the last course of R-CHOP, patients who achieve a complete remission (CR) undergo radiotherapy 5 days a week for approximately 5½ weeks.