The correct answer is 1.
Rationale:
Based on the LYCHOPR protocol "Dose Modifications" section, DOXOrubicin and cyclophosphamide doses in Cycle 1 should be reduced to 75% for patients greater than 75 years old. The doses can be escalated to 100% in subsequent cycles, depending on the patient’s tolerance to the reduced dose. Doses are calculated as follows:
Cyclophosphamide dose = 750 mg/m2 x 0.75 x 1.52 m2
= 855 mg
DOXOrubicin dose = 50 mg/m2 x 0.75 x 1.52 m2
= 57 mg
VinCRIStine dose = 1.4 mg/m2 x 1.52 m2
= 2.1 mg
RiTUXimab dose = 375 mg/m2 x 1.52 m2
= 570 mg
Prednisone dose = 45 mg/m2 x 1.52 m2
= 68.4 mg (rounded to nearest 25 mg = 75 mg) daily x 5 days