Dietary and genetic factors associated with risk for development of colorectal cancer: Case-control study in a Basque population

207 p.To date, case-control studies have revealed inconsistent evidence on the influence of dietary and genetic factors on colorectal cancer (CRC) risk. In order to better elucidate the role of some of these factors in the aetiology of CRC, the main objective of this study was to analyse dietary and genetic factors in a sample of cases and controls from the population-based CRC screening programme of the Osakidetza/Basque Health Service. In addition, taking into account that an unhealthy diet is associated with the risk of tumour recurrence, metastasis and death, the other aim of this thesis was to assess the adequacy of nutrients consumed and diet quality in a group of CRC patients postsurgery. The results showed that the diet of the studied CRC patients postsurgery is inadequate in many respects, including nutrients and food intakes. In fact, this inadequacy is associated with certain health determinants. On the other hand, there are direct associations between CRC risk and high-fat cheese, and inverse associations with fibre containing foods and fatty fish, as well as adherence to a Mediterranean Diet pattern, in the case-control sample analysed. With respect to genetic factors, it was confirmed a CRC susceptibility locus and the existence of associations between modifiable factors and the rs6687758 SNP; moreover, the Genetic Risk Score was associated with CRC. However, further studies are needed to better understand the influence of the dietary habits on CRC prevention and to establish the role of the genetic factors, as well as the contribution of the gene-diet interactions to the risk of CRC in this population