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Colorectal Cancer Risk Factors & Genetics

As with all cancers, there are certain things that put you at risk for acquiring the disease— some of which can be controlled, and some that can’t. And, because there’s no concrete way to know if or when colorectal cancer will develop, it’s highly important to learn more about what those risks are so you can take measures to reduce the likelihood of getting the disease.

 

What Are the Various Types of Genetic Mutations That Can Lead to Cancer?

Mutations in genes cause cancer. Some of these mutations are caused by exposure to our environment, and other mutations are not yet understood. Genetic mutations that are handed down through the family can increase your risk of developing colon cancer, but it’s not a sure bet that it’s going to happen. Let’s take a look at the differences between the various types of genetic mutations associated with colon cancer. 

Acquired Gene Mutations

Genetic changes that occur throughout your life are called acquired gene mutations. Acquired gene mutations are not passed on from one generation to another. Lifestyle choices that increase the risk of acquired gene mutations are smoking, obesity, improper diet, sedentary lifestyle, etc. 

Inherited Gene Mutations

These mutations, called inherited (hereditary) mutations, are present throughout a person’s life in nearly every cell of the body. When it comes to inheriting a genetic mutation that can cause colorectal cancer, the percentage is slim—less than 10%.

An inherited gene mutation can lead to genetic syndromes, which are disorders caused by one or more abnormalities in the genome.

Genetic syndromes associated with colorectal cancer include:

  • Familial adenomatous polyposis (FAP) and Gardner syndrome. These syndromes are caused by inherited changes in the APC gene, which is a tumor suppressor gene that helps keep cell growth in check. Changes in the APC gene can result in hundreds of polyps to form in the colon.
  • Lynch syndrome (hereditary non-polyposis colon cancer, or HPCC). This syndrome is caused by changes in genes that help damaged DNA repair itself. Mutations of genes like MLH1, MSH2, MLH3, MSH6, PMS1, and PMS2 keep DNA errors from being fixed. This can affect growth-regulating genes, thus leading to the possible development of cancer.
  • Peutz-Jeghers syndrome. A syndrome caused by inherited changes in the tumor-suppressor gene STK11 (LKB1).
  • MUTYH-associated polyposis. This syndrome is caused by mutations in the MUTYH gene, which plays a role in how the cell checks the accuracy of DNA when cells divide.

 

If You Have a Strong Family History of Colorectal Cancer

If you have a parent, child, or sibling (a first-degree relative) diagnosed with colorectal cancer, there is a higher likelihood that you will develop this type of cancer in your life. One out of every three people who have been diagnosed with colorectal cancer has a family member who has also received the same diagnosis. Regular cancer screening is highly recommended in such cases before the age of 40, compared to age 45 for those of average risk. In most of these cases, the cause of colorectal cancer is not related to an inherited genetic mutation, but rather a similar lifestyle or exposure to the same environmental factors.

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Genetic Testing for Colorectal Cancer 

Fortunately, there are ways to determine if you are at an increased risk for colorectal cancer based on your genes. Genetic testing for hereditary cancer syndromes can indicate whether you show signs of any genetic syndromes, such as the ones listed above. 

These tests can also show whether family members without obvious disease have inherited the same mutation as a family member who carries a cancer-associated mutation.

Factors that suggest a genetic contribution to colorectal cancer include: 

  • A strong family history of colorectal cancer and/or polyps
  • Multiple cancers in a patient with colorectal cancer
  • Being of an early age at diagnosis 

Talk to your physician about your family's health history to see if genetic testing for colorectal cancer is a good idea for you. 

Colorectal Cancer Risk Factors

 

Other Colorectal Cancer Risk Factors

In addition to genetics, there are other risk factors that are completely out of your control. These can include: 

  • Age. The risk of colorectal cancer increases as people get older. Colorectal cancer can occur in young adults and teenagers, but the majority of colorectal cancers occur in people older than 50.
  • Gender. Men have a slightly higher risk of developing colorectal cancer than women.
  • Family history of colorectal cancer. Colorectal cancer may run in the family if your first-degree relatives (parents, brothers, sisters, children) or other family members (grandparents, aunts, uncles, nieces, nephews, grandchildren, cousins) have had colorectal cancer.
  • Inflammatory bowel disease (IBD). People with IBD, such as ulcerative colitis or Crohn’s disease, may develop chronic inflammation of the large intestine. This increases the risk of colorectal cancer. Keep in mind that IBD is not the same as irritable bowel syndrome (IBS). IBS does not increase your risk of colorectal cancer.
  • Adenomatous polyps (adenomas). It’s important to understand that polyps are not cancer. However, some types of polyps called adenomas can develop into colorectal cancer over time.
  • Personal history of certain types of cancer. If you have a personal history of colorectal cancer or have had ovarian cancer or uterine cancer, you are more likely to develop colorectal cancer.
  • Race. Black people have the highest rates of sporadic, or non-hereditary, colorectal cancer in the United States. 

Sometimes, the lifestyle choices you make can also contribute to your risk for colorectal cancer. Risk factors that you do have some control over include: 

  • Physical inactivity and obesity. If you live an inactive lifestyle (no regular exercise and a lot of sitting) or are overweight or obese, you may have an increased risk of colorectal cancer.
  • Nutrition. Current research consistently links eating more red meat and processed meat to a higher risk of the disease. Other dietary factors have also been looked at to see if they affect the risk of developing colorectal cancer.
  • Smoking. Recent studies have shown that smokers are more likely to die from colorectal cancer than nonsmokers. If you smoke, we recommend that you quit. 

Remember, different factors cause different types of cancer— and although there is no proven way to completely prevent this disease, you may be able to lower your risk. We at RMCC recommend that you take control of your health by understanding your family history, striving to make good lifestyle choices, and seeing your physician for regular colorectal cancer screenings. If the time comes when you need us, know that we are here to help.

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