We will carry out an 8-week double-blind randomized, placebo-controlled clinical trial to evaluate the effects of vitamin D and omega-3 fatty acids co-supplementation on inflammatory biomarkers, tumor marker CEA, and nutritional status in patients with stage ӀӀ or ӀӀӀ colorectal cancer undergoing chemotherapy. The gene discussed is CEACAM5; the disease is colorectal cancer.