P-0268 - Family History and Colorectal Cancer: a Study to Investigate the Incidence of Hereditary and Familial Colorectal Cancer

Abstract

Background: The complete medical approach to colorectal cancer often includes not only the treatment of the individual who is sick, but also requires the study of his family, as cancer is eventually linked to some kind of inherited genetic mutation. It is, therefore, very important to completely understand the epidemiology and the genetic aspects of this type of cancer, in order to successfully assist the patient and his family. This study aims to investigate the incidence of colorectal cancer associated to inherited mutations, classifying them, based on the guidelines of the Brazilian Clinical Genetics Society (BCGS), into three categories: Hereditary (inherited mutations that can lead directly to cancer), Familial (inherited mutations that can predispose to secondary oncogenic mutations) and Sporadic (related to non-inherited mutations). Methods: This research was made based on data collected from 291 patients attended between the years of 2006 and 2011 at the State University of Campinas’ oncology service. Data gathered include several of the patient’s characteristics, such as age at the diagnosis and familial history related to cancer, as well as tumor related information, such as stage of the tumor and pathological findings. This data was analyzed accordingly to the BCGS guidelines and Amsterdam I and II criteria, aiming to determine the role of genetics in each of the 291 cases. Results: 14% of the patients could not be assigned to one of the three categories, because they alone met the Amsterdam criteria for hereditary cancer, but their family did not present, at the time, positive cancer history. 6,5% of the patients were qualified to hereditary colorectal cancer, while 2,5% of them met the criteria for familial colorectal cancer. The rest of the patients (77%) were assigned to the sporadic colorectal cancer group. Conclusion: The amount of individuals with colorectal cancer related to inherited mutations indicates that inheritance does not ensure colorectal cancer manifestation, but cannot be ignored. Further research is needed to point out what’s precisely the inherited mutations role in colorectal cancer. This research also shows that it’s important to provide proper genetic testing for individuals who are suspected to have a hereditary/familial colorectal cancer, but do not meet all the criteria for the diagnosis, after all, they represent an important share of the total analyzed (14%).