The occurrence of colorectal cancer is related to the interaction that takes place at several levels between hereditary factors, environmental and individual ones. Understanding the molecular basis is important because it can identify factors that contribute to the initiation of development, maintenance of progression but also determine the response or resistance to antitumor agents. Understanding colorectal cancer at the molecular level has provided data used for genetic tests of family forms, it defined predictive markers used to select patients susceptible to certain forms of therapy and also for the development of molecular diagnostic tests to detect early non-invasive cancers.

Abbreviations: CIN = chromosomal instability; MMR = mismatch repair genes; MSI = Microsatellite instability, HNPCC = hereditary nonpolyposis colorectal cancer, NSAID’s = nonsteroid anti-inflammatory drugs