• Histologically documented diagnosis of Diffuse Large B-cell Lymphoma or Follicular grade IIIb lymphoma, as defined in the 2017 edition of the World Health Organization (WHO) classification.

• Age ≥ 65 years

• Comprehensive Geriatric Assessment performed at baseline, before start of any treatment.

• Eastern Cooperative Oncology Group performance status (PS) ≤3

• Eligibility for anthracycline containing regimen (R-CHOP or R-miniCHOP)

• No previous treatment for DLBCL or Follicular grade IIIb lymphoma

• Ann Arbor stage I-IV

• At least one site of measurable nodal disease at baseline ≥ 1.5 cm in the longest transverse diameter as determined by CT scan ; or one metabolic active site of disease at baseline FDG-PET scan

• Serum basic levels of Vitamin D \[25 (OH) VitD\] ≤ 40 ng / ml;

⁃ Adequate hematological counts defined as follows:

∙ Absolute Neutrophil count \> 1.5 x 109/L unless due to bone marrow involvement by lymphoma

‣ Platelet count ≥ 80.000/mm3 unless due to bone marrow involvement by lymphoma

⁃ Adequate renal function defined as follows:

⁃ \- Creatinine ≤ 2 mg/dL, unless secondary to lymphoma

⁃ Adequate hepatic function defined as follows:

⁃ \- Bilirubin ≤ 2 mg/dL unless secondary to lymphoma

⁃ LVEF \> 50% at bidimensionally echocardiogram

⁃ Life expectancy ≥ 6 months

⁃ Subject understands and voluntarily signs an informed consent form approved by an Independent Ethics Committee , prior to the initiation of any screening or study-specific procedures

⁃ Subject must be able to adhere to the study visit schedule and other protocol requirements

⁃ Men must agree to use one of the below reported acceptable method of contraception for the duration of the study and for 3 months after receiving the last dose of immunochemotherapy, and to not donate sperm while on study.