A method is disclosed for the determination of 5-ASA efficacy in preventing and/or treating CRC in a mammalian, which comprises the analysis of the inhibition of the β-catenin pathway in presence of 5-ASA. More in details, the method comprises measuring the expression of at least one gene involved in the regulation of the β-catenin signalling pathway, such as μ-protocadherin, E-cadherin, β-catenin, Axin1, ICAT, p21waf−1 and the expression of onco-suppressor genes, such as KLF4 and CEBPα. Gene expression can be measured in accordance to the methods commonly available in the art such as QRT-PCR and immunohistochemistry.