Cancer and oncogenetics

Around 5% of cancers diagnosed develop due to a genetic predisposition. There are personal and/or family elements suggestive of these familial hereditary forms, which should prompt people who are likely to be carriers of a predisposition to seek genetic counseling.

What is cancer?

Cancer is a genetic disease that occurs following the appearance - spontaneous or due to exposure to a carcinogenic agent (tobacco, UV, etc.) - of the accumulation of mutations in the genes of a cell. The cell becomes abnormal and then multiplies in an anarchic way until it forms a tumor. The genetic alterations are in this case only present in the cancer cells. They are called "acquired" or "somatic". 

In the case of a genetic predisposition to cancer, a mutation is present from the outset in all the cells of the organism, including those used to form the eggs and the spermatozoa. It is called "constitutional". It can be transmitted to the embryo at the time of conception. People carrying this mutation are then at a higher risk than the general population of developing one or more cancers during their lifetime. 

In France, hereditary cancers constitute about 5% of cancers, and more than 80 predisposing genes have been identified. These are not just any genes, but genes that have a role in controlling the proper functioning of the cell.

Download the monitoring and management guide for women at very high risk of breast and/or ovarian cancers