A Study to Evaluate the Effect of Vitamin D on PFS in Indolent Non-Hodgkin's Lymphoma

Inclusion Criteria:

Each of the following criteria must be met in order for a patient to be considered eligible
for registration:

- Biopsy proven (with hematopathology review at one of the participating sites to
confirm correct histology in accordance with World Health Organization) indolent
lymphoma to include the following diagnoses:

- Grade 1, 2, or 3a follicular lymphoma

- Small lymphocytic lymphoma (CLL excluded)

- Marginal zone lymphoma (nodal or splenic)

- Mucosal-associated lymphoid tissue

- Measurable disease defined by Lugano criteria

- No prior anti-lymphoma systemic therapy; prior radiation therapy allowed

- Age 18 or over

- Ann Arbor stages II, III or IV

- Patients with follicular lymphoma must have PET FDG-avid lymphoma and fulfill Low
tumor burden by Groupe D'Etude des Lymphomes Folliculaires (GELF) criteria:

- No mass > 7 cm

- < 3 distinct masses of greater than 3 cm

- No B symptoms

- No splenomegaly > 16 cm by computed tomography (CT) scan

- No risk of vital organ compression

- No leukemic phase > 5000/µl circulating lymphocytes (except for in patients with
splenic marginal zone diagnosis)

- No cytopenias (platelets < 100,000/µl, hemoglobin < 10 g/dl, or absolute
neutrophil count < 1500/µl)

Exclusion Criteria:

The following criteria will prevent inclusion of an inappropriate subject into the trial:

- Osteoporosis requiring prescription treatment

- Known symptomatic primary hyperparathyroidism

- Hypercalcemia defined as above the institutional normal range (corrected for albumin
when albumin levels are below normal)

- History of calcium-related kidney stones

- Creatinine > 1.5X above upper limit of normal

- Women who are known to be pregnant or who plan to become pregnant while on rituximab
treatment