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Does your genetic makeup put you at greater risk of colon cancer?

December 01, 2015 | William E. Karnes, MD
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We all have a 1 in 20 chance of getting colon cancer. You read that right: 1 in 20. It is estimated that 14,510 new colon cancer cases will be diagnosed in California in 2015.

Before you panic, the key thing to know about colon cancer is that it is preventable. Unlike other cancers, colon cancer has a precancerous stage that can last 10 years or more before cancer develops. It’s kind of like a caterpillar turning into a butterfly — with the caterpillar being a polyp, which is easy to find and remove during a colonoscopy before it transforms into cancer.

By engaging in regular colorectal cancer screening and removing polyps as they develop, you can reduce your risk of colon cancer to something more like 1 in 200.

Also, some people face a slightly higher risk of developing colon cancer than others, including men and African-Americans.

The biggest threat, however, lies in your genes.

Is colon cancer genetic?

Cancer forms when genes mutate. In most cases, we acquire these mutations over time. That means the longer we have our colons, the more likely a cell in our colon will mutate, form a polyp and develop into cancer.

However, if one of your parents passes on a mutated gene, every cell in your body will have that mutation, making you more susceptible to developing cancer. It’s also possible that a mutated gene could be formed during conception, meaning you would be the first in your family to have that gene.

We have identified a number of genes that increase your risk of colon cancer, and some are more common than you would expect. For example, it’s estimated that 1 in 300 people have Lynch syndrome, which increases a person’s risk of developing colorectal cancer over their lifetime up to 80 percent. In Orange County, that translates to 10,000 people.

When to consider genetic counseling

Genetic counseling can be a great tool to help you spot a potential increased risk of colon cancer.

Genetic counselors are trained to look at a family tree and make an educated guess about which gene might be at fault. Then, using a simple blood test, they can check for a disorder such as Lynch syndrome.

These risk factors might prompt you to consider scheduling genetic counseling:

If you’re one of the rare people in which the mutation occurred at conception and wasn’t passed down from your parents, you may want to consider genetic counseling if you are diagnosed with colon cancer at a young age. This can alert your children and grandchildren to their potential increased risk.

If a genetic mutation is confirmed, your genetic counselor will go over what that means for you, how you can protect yourself and who else in your family may be at risk.

How to manage your risk

If you discover you have an increased risk of colon cancer due to your genetics, what then?

While the management strategy differs based on the gene involved, it’s almost certain your doctor will recommend earlier and more frequent screening. Best practices advise the average-risk person begin screening every 10 years at age 50.

Along with regular screening, follow these tips to reduce your risk of developing colon cancer:

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