Prephase Treatment With Prednisone +/- Vitamin D Supplementation Followed by Immunochemotherapy

This is an open-label, multicenter, randomized phase III trial. The study plans to randomize patients with a 1 to 1 ratio to Arm A (Standard arm) or Arm B (Experimental arm). All patients of both arms will receive a prephase with oral prednisone before 6 cycles Q21 of immunochemotherapy with R-CHOP or R-miniCHOP at standard doses; patients in the Experimental arm (Arm B) will receive also a prephase therapy with VitD and a supplementation of VitD during the intere period of immunochemotherapy according to a prefixed schedule. Choice of type of immunochemotherapy will not rely on Comprehensive Geriatric Assessment result, but treatment at reduced doses with R-miniCHOP is highly recommended option for UNFIT and FRAIL patients.