Calcium plus vitamin D may be effective in the prevention of colorectal adenoma recurrence. The aim of this study is to investigate the effect of supplementation with calcium plus vitamin D on the recurrence of colorectal adenomas.

Colorectal adenomas are well-known to be precancerous lesions that develop into colorectal cancers on the basis of the adenoma-carcinoma sequence. The effects of screening for colorectal adenomas and removing precancerous lesions on the prevention of colorectal cancer have been established. Because of the high recurrence rates of colorectal adenomas in patients who have undergone polypectomy, the potential chemopreventive agents that may reduce the risk of colorectal adenoma recurrence need to be investigated. Since laboratory and epidemiologic evidence suggests that calcium or vitamin D may help prevent colorectal adenomas, we conduct a randomized, placebo-controlled, prospective clinical trial to study the effect and safety of calcium plus vitamin D supplementation in prevention of colorectal adenomas recurrence.

Inclusion Criteria:

• Individuals aged 18-65years
• Individuals who had at least one histologically confirmed colorectal adenoma removed within three months before recruitment
• Individuals without a history of familial polyposis
• Those who voluntarily sign the consent form after being fully informed and understanding the purpose and procedures of the study , characters of the disease, effect of medications, methods of related examinations, and potential risk/benefits of the study

Exclusion Criteria:

• Patients who are hypersensitive or intolerant to the drugs
• Patients who are intolerant to another colonoscopy examination
• Patients with hypercalcemia or urolithiasis
• Pregnant women, women during breast-feeding period, or women with expect pregnancy
• Patients with diabetes mellitus, severe heart or renal disease, or cancer history
• Patients with a history of subtotal gastrectomy or partial bowel resection
• Patients who are not able to cooperate
• Individual who are involved in designing, planning or performing this clinical trial
• Patients with medical conditions who are not appropriate to participate the study
• Patients who are taking aspirin, NSAIDs or COX2 inhibitors
• Patients who are taking folic acid or Butyrate.
• Patients with IBD