The aim of this work is to assess the of role of Vitamin D supplement on tumor response, inflammation and apoptosis in patients with stage II or III colorectal cancer receiving chemotherapy using BAX protein and Tumor necrosis factor - alpha (TNF- α) both are measured at baseline and after 6 months.

This randomized, controlled parallel study will be conducted on 44 patients with Stage II or III colorectal cancer. Patients will be recruited from Clinical Oncology

Department, Menoufia university Hospital, Menoufia, Egypt. The patients will be randomized using sealed envelope method into the following two groups:

Group I (Control group; n=22) which will receive FOLFOX (leucovorin, fluorouracil, and oxaliplatin) or XELOX (capecitabine and oxaliplatin).

Group II: (Vitamin D group; n=22) which will receive the same chemotherapy regimen plus Vitamin D for 6 months.

Markers to be measured:

• BAX protein as a marker for apoptosis will be measured at baseline and after 6 months.
• Tumor necrosis factor - alpha (TNF- α) as a marker of inflammation will be measured at baseline and after 6 months.

Inclusion Criteria:

• Patients with histologically and radiologically confirmed diagnosis of stage II or III colorectal cancer.
• Performance status 0-1 according to the Eastern Cooperative Oncology Group (ECOG).
• Patients who received FOLFOX or XELOX as first line chemotherapy.
• Both genders.
• Age ≥18.
• Patients with adequate hematologic parameters (white blood cell count ≥3000/mm3, granulocytes ≥1500/mm3, platelets ≥100,000/mm3, hemoglobin ≥ 8 gm/l).
• Patients with normal renal functions.
• Patients with normal hepatic functions.
• Patients with sufficient 25(OH) Vitamin D level (30-100 ng/mL).

Exclusion Criteria:

• Patients with metastatic colorectal cancer (CRC).
• Patients with parathyroid disorders.
• Patients who are taking vitamin D-containing supplements (>800 IU/day) unless they discontinued vitamin D supplementation at least 2 months prior to enrollment.
• Patients had a history of hypercalcemia.