Abstract: The present invention relates to a method for the prevention of cancer or the initiation and/or progression of cancer in a human comprising administration to the human a combination dosage of a cyclooxygenase (COX) inhibitor, a vitamin D3 including analogues and metabolites thereof and calcium. In a further embodiment the invention relates to the use of the combination dosage for the preparation of a medicament and to such pharmaceutical preparations. In a further aspect the invention relates to a method for reducing the effective dosage of ASA in a chemoprofylactive treatment of colorectal cancer in a human by co-administration with a non toxic dosage of a vitamin D3 including analogues and metabolites thereof and Ca in the form of a combination dosage.