A big collaborative study search the significance of small genetic variations in colorectal cancer

The Gastroenterology Department of Hospital del Mar, IMIM (Research Institute of the Hospital del Mar) and CREAL (Centre for Research in Environmental Epidemiology) researchers, together with the Gastroenterology Service of Hospital Clinic of Barcelona and the Institute for Biomedical Research August Pi i Sunyer (IDIBAPS), have led a study that identifies the correlation between susceptibility genetic variants and different clinical characteristics and relatives of colorectal cancer patients. This study, conducted within the framework of the project EPICOLON-initiative of the Spanish Association of CIBER Gastroenterology-and Liver and Digestive Disease (CIBERehd), just published in the journal Gastroenterology, leader of the specialty. It’s a multicentre with population-based multicentre that collected every patients with Colorectal Cancer (CCR) in 25 hospitals in Spain. The results could help improve detection of Colorectal Cancer Family by identifying people with increased susceptibility to develop this type of tumor.

Colorectal cancer is one of the most common cancers in Western countries, being the second leading cause of cancer death in our country. Genetic and environmental factors play a role in its development. The inherited susceptibility is responsible for approximately 30% of all cases of CCR. Hereditary colorectal cancer accounts for less than 5% of cases and other inherited predisposition may be attributed to the combination of a large number of polymorphisms or SNPs (single nucleotide changes in the DNA strand). These SNPs are common and low penetration, which means, by themselves give to a person a low probability of having the disease. Even so, depending on their number and associated with other factors, the risk of developing it may increase.

Study keys
Recently association studies (Genome-wide association study, GWAS) have identified 10 common genetic variants of low penetrance susceptibility to CCR. "There is not a relationship of direct cause-effect between having these genetic variants and suffering colorectal cancer, but they provide some susceptibility to suffer it", explain the coordinators of the study, Dr. Montserrat Andreu, chief of Section of the Gastroenterology of Hospital del Mar, and Dr. Sergi Castellví-Bell, senior researcher of IDIBAPS-Hospital Clínic. The aim of the study is to establish genotype-phenotype correlation between common genetic polymorphisms of low penetrance (SNPs) identified firmly in previous studies and personal characteristics (demographic, clinical and referring to the tumor) and family members of patients who suffer colorectal cancer. In this sense, Dr. Andreu explains that "the identification of these individuals is achieved through the identification of genetic variants and this probably may increase the accuracy of population risk stratification and screening policies". According to Dr Sergi Castellvi-Bell "it’s an important first step to identify, through genetics, the risk of suffering a disease and enable thus a more personalized treatment."

For example, Dr. Andreu specifies that "the results obtained in this study have been replied in two independent groups of patients with CCR and found evidence that patients carrying the susceptibility allele of the 8q24.21 region at higher risk of familial aggregation of CCR and the susceptibility allele of 8q23.3 have a more advanced tumor diagnosis". This suggests a possible aggressive behavior of tumor in patients with this genetic variant. Dr. Sergi Castellví-Bell adds that “the interaction between the 8q22 and 16q22 genetic variants are found more often in patients with a history of previous or synchronous colorectal adenomas, suggesting an increased risk of developing colorectal adenomas in these patients”.
 

Source: Parc de Salut MAR