What You Need to Know about Genetics and Colorectal Cancer

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What You Need to Know about Genetics and Colorectal Cancer

Quite a few things can increase your risk of developing colon cancer. Some of these factors are controllable, such as weight, diet, smoking, and alcohol consumption. Other factors, such as age and genetics, are not. 

In recent years, research has shown that there is a relationship between gene mutations and several types of cancer, including colon cancer. These mutations may occur due to environmental causes, be inherited, or have no known cause.

The Types of Genetic Mutations Related to Colorectal Cancer

There are two types of genetic mutations: acquired and inherited. Let's explore the various mutations linked to colon cancer.

Acquired Gene Mutations

Most cases of colon cancer are due to acquired gene mutations that develop over time. This type of genetic mutation is not passed from one generation to the next. Rather, genes can mutate on their own over time, often related to the risk factors that each person can control.

Acquired mutations can occur for various reasons, one of which is lifestyle choices, including:

  • Smoking
  • Eating an unhealthy diet with sugar, processed foods, and red meat.
  • Being obese
  • Drinking alcohol
  • Leading a sedentary lifestyle 

Your oncologist can run biomarker tests on the tissue removed in a biopsy or during surgery to see if any genetic mutations are present. Based on the results, specific colon cancer treatments may be recommended because they are known to counteract the genetic mutation and slow the growth of cancer cells. Targeted therapies are usually combined with other types of treatment, such as chemotherapy and radiation therapy

Inherited Gene Mutations

Approximately one-third of patients with colon cancer have at least one family member with the same disease. The reason for this familial connection isn’t always clear. It could be due to an inherited gene, shared risk factors such as diet and exposure to smoke, or a combination of these.

One of the best things you can do is understand your own health risk and your family history, if possible, especially your parents, siblings, and children. If any family member was diagnosed with colorectal cancer before the age of 50, you have a higher risk of developing the same condition. 

Hereditary Syndromes Associated With a Greater Colon Cancer Risk

About 5% of all colon cancers are related to a hereditary genetic syndrome. 

Lynch Syndrome

Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC), is a rare condition that can increase the risk of developing colorectal cancer. Estimates suggest that those with Lynch Syndrome have an increased chance of developing colon cancer. 

Lynch syndrome is linked to an increased risk of developing polyps, called adenomas, in the colon or rectum. These can be non-cancerous (benign) at first and then become cancerous (malignant) over time. In individuals with Lynch syndrome, polyps are more likely to become cancerous than someone who does not have this genetic syndrome.

Familial Adenomatous Polyposis (FAP) and Attenuated FAP  

FAP is a condition in which polyps develop in the colon or rectum before the age of 20. Over time, the number of polyps can increase and become malignant, leading to cancer by the age of 40. Attenuated FAP, on the other hand, is characterized by the presence of fewer than 100 polyps in the colon and is often associated with slower development of cancer. In these cases, cancer usually appears around the age of 55. 

A mutation in the APC gene causes both FAP and attenuated FAP. If your immediate family member has this gene mutation, you have a higher risk of developing one of these conditions.

Peutz-Jeghers Syndrome (PJS)

Caused by a mutation in the STK11 gene, Peutz-Jeghers syndrome (PJS) is a medical condition characterized by the growth of non-cancerous polyps in the gastrointestinal tract. These polyps can develop in the stomach, colon, or small intestine, resulting in bleeding and pain. A PJS diagnosis means you have a slightly higher risk of developing colorectal cancer.

MUTYH-Associated Polyposis (MAP)

MUTYH-associated Polyposis, commonly known as MAP, is an inherited disorder that triggers the growth and development of multiple adenomatous polyps in the colon and rectum. The MUTYH gene is associated with a range of other health conditions in addition to colorectal cancer. While typical cases of MAP result in the emergence of 10 to 100 polyps, some patients may have more than 1,000 polyps.

Screening for Colon Cancer Is Important for All Risk Levels

If you have no family history of colorectal cancer, you should begin screening at the age of 45. However, if you have a family history of this type of cancer, you should begin screening by the age of 40. The screening method may also differ depending on your risk profile. Those at higher risk may begin with colonoscopies instead of stool samples, which may be the first step for those at average risk.

Learn more about colon cancer screening. 

How to Discover if You Have a Gene That Could Lead to Colon Cancer

There are some genetic tests that will tell your doctor if an inherited genetic syndrome is present. A genetic counselor can help you decide if you and your family would benefit from cancer genetic testing. 

After testing, the genetic counselor will examine and interpret the results. If you have a gene mutation associated with colon cancer, it is a good idea to inform your family members so they can also get tested. Just because the gene is present in one family member does not mean everyone has it, so each individual should be tested separately.

Colon Cancer Treatment in the Atlanta Area

If you’ve recently received a diagnosis of colorectal cancer, the team at Radiotherapy Clinics of Georgia is available to assist with the radiation therapy portion of the treatment plan. Located in the greater Atlanta area, it’s important to find a radiation therapy clinic that’s convenient since most patients will go five days a week for a few weeks to receive treatments.

Request an appointment with one of our radiation oncologists to learn more about colon cancer radiation treatment options.