Is Cancer Hereditary? Understanding Cancer And Genetics
Cancer is a complex disease caused by genetic mutations and is considered one of the most common human diseases influenced by genes. Many people worry about whether cancer is hereditary, especially when they notice multiple cases in the family.
To help you understand if cancer is indeed hereditary, here are a few basic facts about the genetics involved in the development of different types of the disease.
Is cancer hereditary?
Current research estimates that about 5–10% of all cancers are hereditary. This means that while most cancers are not directly inherited, some individuals inherit gene mutations that increase their susceptibility.
Many apparent “family cancers” may be due to shared environmental factors or lifestyle habits, such as tobacco use, alcohol consumption, or UV exposure, rather than strictly genetic inheritance.
Hereditary vs Acquired (Sporadic) Cancer
Cancer is a result of uncontrolled cell division, which is caused by a genetic mutation. A mutation is an abnormality that affects how a cell functions. For instance, a mutation may stop a gene that restricts cell division to stop working or multiply rapidly, leading to an indiscriminate division in both cases. Such mutations can be inherited or acquired.
Inherited (germline) gene mutation: Such mutation is present in the sperm or the egg cell from which the fetus was formed. Since the mutation was present in the zygote, it is transferred to the fetus. Individuals carrying these mutations have a higher lifetime risk of developing certain cancers, but inheritance does not guarantee cancer.
Acquired (somatic) mutation: Such a mutation develops later in life due to environmental exposures, or an error in DNA replication. Such a mutation is passed only to the cells created from the cell that suffers from the mutation. It doesn’t affect every cell in the body. Not being present in the reproductive cells, it isn’t transferred down generations either.
What happens if one inherits a gene mutation?
An inherited mutation increases cancer risk but does not ensure that cancer will develop. If the healthy copy of the gene from the other parent remains intact, cancer may never occur. However, if the healthy gene later acquires a mutation, cancer can still develop.
How to recognize a family cancer syndrome?
If you see cancer cases in your family and want to find out if cancer is genetic in your family, here are some indicative factors:
Multiple cases of the same type of cancer in the family
Higher-than-expected frequency of cancer
A person developing more than one type of cancer
Cancer occurring in siblings or successive generations
Early-onset cancers (diagnosed before age 50)
With genetic testing now available for some hereditary cancers, it is highly advisable to consult a specialist or genetic counsellor if these patterns appear.