Inherited Genetic Alterations and Cancer

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Cancer is, unfortunately, a common disorder. Most cancer is not due to inherited factors, but a tiny proportion of people have inherited genetic alterations that put them at increased risk of developing cancer.

Factors that could suggest an inherited genetic cause for cancer include younger than expected ages at diagnosis, more than one cancer in one person, or several relatives in one family being affected by particular types of cancer.  

Genes are small chunks of the DNA genetic code that we inherit from each of our parents. We have two copies of most genes, one of which we inherit from our father, and the other of which we inherit from our mother. 

Certain genes work to prevent against the development of cancer. Alterations in such genes can interfere with their function, leading to an increased risk cancer. 

If you carry a genetic alteration, each of your children (male or female), and your siblings (male or female) have a 50% (1 in 2) risk of inheriting the same alteration.


The risk of cancer associated with gene alterations depend on a number of factors:

  1. The gene involved (BRCA1-v-BRCA2)

  2. The age and gender of the individual (male-v-female)

  3. If risk-reducing strategies are undertaken (risk-reducing surgery)

  4. Environmental and other genetic factors