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Genes and cancer risk in families

When there is cancer in your family, it’s normal to worry that you will develop cancer as well. But even if 1 or 2 family members have been diagnosed with cancer, it doesn’t mean that you will. This is especially true if the family member is not a first-degree relative (your parent, child or sibling) or if the cancers are of different types.

How do I know if the cancer in my family is hereditary? Only about 5 to 10% of all cancer cases are hereditary, meaning they are caused by an inherited gene mutation.

A cancer might be considered hereditary if:

  • the cancer has developed in more than 1 generation
  • family members developed cancer when they were younger than 50 years old or at a younger age than usual for that type of cancer
  • family members have each had more than 1 type of cancer

There are genetic tests available to test for gene mutations for some types of cancer. Genetic testing should always be done at a clinic that also provides counselling and education. Some people may decide not to have genetic testing because they prefer to not know if they are at increased risk of cancer or other inherited diseases.

image of a family
What can I do if I have increased risk of developing cancer because of my family history?

Depending on how high your risk is, cancer specialists may recommend ways to help prevent or detect cancer early.

Your options may include:

  • changing your lifestyle
  • having genetic testing
  • having regular checkups
  • beginning screening at an earlier age or having screening tests more often
  • having preventive surgery
  • taking drugs that may help lower risk
Do I need to tell my kids?

It’s important for your children to know about their family health history. If you or other family members have had genetic testing that found a gene mutation, your children may also choose to get tested when they are older.