Cancer screening and genetic counseling

Abstract

Familial predisposition to cancer has been recognized for many years. The discovery fifteen years ago of some of the genes that are involved in the heritance of very common malignant diseases, like breast and colorectal cancer, has represented a major advance, and a challenge, for cancer prevention. Colorectal cancer is the first incident malignancy in our population, and breast cancer can affect 1 in 12 women in some European countries. There are several models that calculate the risk of cancer based on personal conditions or familial history. Testing for genes related to hereditary cancer allows the selection of individuals who will really benefit of prevention measures in such high prevalent diseases. The majority of these genes belong to the category of tumor suppressor genes, a second genetic hit is always needed for tumor developing. Epigenetics, defined as the factors that modulate the penetrance of a genetic disease, play an important role in hereditary cancer predisposition. Due to the complexity of genetics and clinical management of the hereditary cancers, all individuals with risk should be seen at Cancer Genetic Counseling units or Cancer Family Clinics. The clinicians that work in these Units should have special training in genetic counseling, cancer genetics and hereditary cancer management. Cancer Genetic Counseling is a communication process in which genetics, medical and psychological issues related to hereditary cancer risk development and prevention options are discussed with the individuals and families. Counseling must not be biased, and individual autonomy must be protected. A collaborative model between counselor and patient is preferred, and all the following points should be included in the informed consent process: options for risk estimation if genetic testing is not done,information on the specific test (accuracy, limitations), interpretation of all possible test results, implications of results for the individual and family, confidentiality issues, risk of psychological distress, options for care after testing and limitations. Some ethical and legal issues arise in the global processes of cancer genetic counseling that must be recognized and taken in account. Many questions have still not answers in this field. Nonetheless, it would be inappropiate to dismiss the potential benefits of genetic counseling as a reaction to sporadic uncritical application of genetic testing. This paper will review the genetic basis and the opportunity for screening and prevention of the hereditary predisposition to cancer, mainly focused to breast, ovarian and colorectal cancer.