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Hereditary and Familial Cancer

Head of Unit: Miguel Urioste

Cancer is a multifactorial disease due to the combined effect of genetic and environmental factors. A small proportion, that is estimated approximately in 5% of all tumours, has a hereditary character. Hereditary cancers are the consequence of germinal mutations in specific genes that increase the susceptibility to develop a neoplasia. This susceptibility is transmitted to the family members with different hereditary patterns. The susceptibility to develop cancer is inherited, which doesn’t imply the certainty in development in all cases. More than 50 genes involved in cancer predisposition have been identified until now and techniques for study alterations in these genes have been developed.

It is important to identify families with possible hereditary cancer types because family members will benefit from efficient measures, not only in early detection but also in the prevention of tumours. It is commonly observe, that in families with hereditary cancer, several members often inherit the same type of cancer, from generation to generation, and that this usually occurs at early ages: between the ages of 40 and 50 in most frequent syndromes like Breast/Ovarian and Colorectal Syndromes. Likewise, it is common to observe bilateral forms when paired organs are affected (breast, kidneys, etc). Another characteristics of hereditary cancer are the presence of several primary tumours in the same individual, and the association of cancer with development anomalies. When a practitioner recognises one or more of these symptoms within a family, he could refer her to a Familial Cancer Unit, or otherwise to a Clinical Genetics or Medical Oncology Service.

Genetic and inheritable diseases can reappear in families, circumstance which entails new responsibilities for the medical professional. The attention of families with hereditary cancer requires Genetic Counseling specialists who will evaluate the individual risk for each member of the family, and the appropriate genetic testing. Through genetic counseling, patients with hereditary predisposition to cancer receive information on: 1) The probability to develop a neoplasia. 2) The probability to transmit the cancer predisposition to their offspring. 3) The probability that, they in turn, have to develop a neoplasia. 4) The prognosis and the strategies for the early detection and the most suitable therapeutic approach.

To evaluate the family and personal implications of hereditary cancer and for the making of decisions, it is essential that patients receive psychological support. Knowing the carrier’s condition of a gene alteration, has a deep repercussion and it is therefore, not unusual to observe important emotional disorders that require the attention of a professional psyconcologist.

It is not always possible to carry out specific genetic testing in every case, because there are entities in which the responsible gene is still unknown. The patients should be informed about which the most adequate genetic studies are in their case. They should also know what consequences are expected from the positive results as much as from the negative ones. The genetic studies should always be carried out by highly trained personnel in very competent laboratories. It must be taken into consideration that not all techniques have the same resolution level and the interpretations of results are often complex and in consequence, should be carried out by qualified personnel, with ample experience in the Genetics and Molecular Biology fields.

Another aspect of hereditary cancer which has an important impact in families, is the follow up of individuals at risk. In the clinical practice, nowadays, three main procedures exist to manage these situations: a) Medical surveillance; b) Chemoprevention; and c) Prophylactic surgery. The mostly used procedure is medical surveillance, mainly in Medical Oncology Services, Gynaecological Services and Digestive Services. Consensus recommendations exist for individuals with the most frequent cancer predisposition syndromes, like Breast/Ovarian Cancer Syndrome (BOCS), Lynch and Cowden syndromes, Familial Adenomatous Polyposis (FAP), Multiple Endocrine Neoplasia (MEN), or Neurofibromatosis. Chemoprevention is still under research in most situations. Prophylactic surgery allows primary prevention and can be applied in FAP patients, BOCS patients and to a lesser extent, in Lynch syndrome patients.

When the responsible genetic alteration in a family is unknown, all members at risk (usually the first grade relatives), will be under very close medical surveillance. Knowing the family´s mutation is an advantage, because the follow up will be restricted to those family members who are carriers of the alteration.