Inherited genetic defects occur when people are born with a flaw in their DNA. When this flaw takes place in a gene that is involved in cell division, in cell natural death (apoptosis) or in the repair of cell damage, the chance of developing cancer can be increased." /> hereditary cancers, hereditary diseases, gene BRCA1, gene BRCA2 | Anticancer Fund

Is cancer hereditary?

In more than 90% of the cases, cancer is not hereditary. However, some cancers are associated with inherited genetic defects.

Inherited genetic defects occur when people are born with a flaw in their DNA. When this flaw takes place in a gene that is involved in cell division, in cell natural death (apoptosis) or in the repair of cell damage, the chance of developing cancer can be increased. The level with which the risk of having cancer increases depends on the precise defect. Very few and infrequent defects are known to systematically lead to the development of cancer.

For instance, defects in one of the two genes called BRCA1 and BRCA2 are known to increase the risk of breast cancer and ovarian cancer. The risk of developing breast cancer before 70 in women with a mutation in these genes is about 65% for BRCA1 and 45% for BRCA2. Genetic counseling to check for inherited genetic defects associated with a higher risk of breast cancer could be useful if a relative of the first degree (a sister, mother or daughter) has been affected by breast cancer at a young age or in both breasts, or if multiple relatives in the same side of the family have been affected by breast cancer, including male breast cancer.

Lynch syndrome known as well as hereditary nonpolyposis colorectal cancer is another inherited condition in which the probability of developing cancer, especially colon cancer is higher than the average population. Other cancers associated to this condition are cancers of endometrium, ovary, stomach, hepatobiliary tract, small intestine, upper urinary tract, brain and skin. There are some criteria to suspect the presence of Lynch syndrome in a family, for example when at least three first degree relatives had colon cancer, colon cancer was present in two successive generations and somebody younger than 50 years was affected. In cases like this, genetic counseling can be considered.

Other hereditary forms of cancer are less frequent and carry their own characteristics in terms of genetics, cancer location and increase of risk. The heredity of cancer is a complex matter because a lot of factors are involved. If you believe you have reasons to be worried, you can ask your doctor who might refer you to a specialist in cancer genetics.

For information about the heredity of another cancer, please send an e-mail to info@anticancerfund [dot] org. We will then provide you with the most accurate answer possible.