There is substantial research on cancer and genetics, but the correlation isn’t as clear as many think. While individuals may be aware of their family history of cancer or assume that cancer is hereditary, there are specific kinds of cancer that pose a greater risk for family descendants. The genetics of cancer are endlessly complex, and research uncovers new and often contradictory data all the time. Still, there is solid data on the genetics of cancer and how much risk is associated with specific types. 

Genetics and Cancer

To be clear, cancer is genetic, but not all cancers are hereditary. Geneticists often divide gene-related cancers into two categories, inherited cancers and non-inherited cancers.

Inherited cancers are caused by genetic changes passed down from generation to generation. These types of cancers run in families, and individuals with these mutations are more likely to develop the cancer associated with that gene. The best-known example of an inherited cancer is the mutated BRCA1 or BRCA2 gene. Individuals with the mutated BRCA1 or BRCA2 gene are more likely to develop breast cancer. Critically, inheriting a cancer gene only predisposes an individual to that type of cancer. 

Non-inherited cancers are defined as cancers caused by a genetic change that occurred during the person’s lifetime. Also known as acquired or sporadic cancers, these mutations are usually caused by environmental factors like smoking, radiation exposure, chemicals, diet, alcohol, or sun exposure. Many age-related cancers are also caused by non-inherited gene mutations. 

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What Percentage of Cancers Are Inherited?

According to most medical research, between 5% and 10% of cancers are inherited. While the share of diagnoses due to an inherited predisposition to cancer is small, it has an outsized impact on the families with those genes. Sometimes referred to as “family cancer syndrome”, a family history of cancer can be devastating and, in many cases, impact individuals at an early age. 

It’s important to remember that not all families with recurring cancer diagnoses are predisposed to hereditary cancers. There are also environmental factors, such as smoking, poor diet, or obesity, that contribute to the risks of non-inherited cancers. 

Genetic Testing for Cancer

Recently, private companies have developed cancer genetics tests for common inherited cancers, including breast cancer and colorectal cancers, among others. Genetic testing can help individuals with a genetic disposition to cancer through active monitoring, early detection, and focused treatment. 

So, Will I Get Cancer If My Mom Had It?

Not necessarily. Only about 5-10% of cancers are inherited, and the odds of having the same diagnosis as a parent or family member are still statistically rare. It’s important to monitor your health and consider gene testing if your family has a history of inherited cancers, and tell your doctor about your family’s history. 

Prevention Is In Our Genes

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