Your family's health history can hold important clues about your risk of developing cancer. This includes first-degree relatives (parents, siblings, children) and second-degree relatives (grandparents, grandchildren, uncles, aunts, nephews, nieces, and half-siblings).
Genetic mutations cause cancer, and sometimes these genetic mutations are hereditary. However, only 5-10% of cancers are caused by an inherited genetic mutation.
While some people think that "cancer runs in their family," it's important to understand that cancer may result from shared environmental exposure or similar behavior, such as having several members of the same family smoke.
It also necessary is to understand that even if you have an inherited genetic mutation, it doesn't mean you will develop cancer.
Understanding your family's health history and being aware of your potential risk of having an inherited genetic mutation may help to predict your risk of developing cancer.
It's important to share your family's health history with your primary care physician and/or your oncologist. Hence, they are also aware of your potential risk and can recommend proper cancer screening.
If necessary, they can also order genetic testing to understand better if you are a higher risk, how to recommend the best options for reducing your risk, and/or the most effective treatment options if you have developed cancer.
A tool from the American Surgeon General that you can use to keep track of your family health history is My Family Health Portrait.
What if I don't know my family history?
For some people who don't know their family history, their best defense is to understand other risk factors (behavioral and environmental) they may have, become familiar with signs and symptoms to be aware of, and follow recommended cancer screenings. This will hopefully help to find cancer at an earlier stage when it is easier to treat. Other things that can help are outlined on our Lowering Your Cancer Risk page.