What Causes Colon Cancer?

Most of us know someone who has battled colon cancer. It’s the third most common type of cancer in the US. And it’s the second most common cause of cancer deaths in men and women combined. Even though colon cancer happens so often, doctors still don’t know exactly what causes it.

The one thing that all types of cancer have in common is that the genetic material of the cell- the DNA- is damaged or “mutated.” Many things can damage DNA: chemicals in our food, water and air, radiation, viruses and even age. 

When the damage happens at the wrong spot, cells can grow out of control, making a mass called a tumor. Sometimes, the mutations allow the cells to escape their normal tissues and move to other parts of the body where they don’t belong. When mutated cells move to other organs or lymph nodes, it’s called “metastasis” or “mets.” 

While we don’t know what causes colon cancer, we do know there are conditions that increase a person’s risk of getting colon cancer. Knowing you have risk factors for cancer can be scary. We mentioned in an earlier article that a risk factor doesn’t cause cancer and it doesn’t mean you’ll ever get cancer. But, having one or more risk factors for colon cancer means that you have an increased risk compared to someone who doesn’t have any risk factors.

Risk factors can be looked at as things you can change and things you can’t change. For example, age, gender and family or personal history of disease can’t be changed. The older you get, the higher your risk for developing many diseases, including cancer. The risk factors you can try to change are called “lifestyle factors.”

Let’s take a look at some of the risk factors for colon cancer that you can work on changing.

  • Physical activity: A sedentary lifestyle is associated with an increased risk of colon cancer. Over 50 studies of adult Americans have looked at exercise’s effects on colon cancer. People who increase the duration, intensity or frequency of exercise can reduce their risk by 30% compared to people who don’t exercise.
  • Diet: Eating a lot of fatty, low fiber and sugary or highly processed foods like hot dogs and lunch meats can increase your risk of colon cancer. People who eat lots of veggies, fruits and whole foods, tend to have a lower risk of colon cancer.
  • Weight: People who are overweight or obese have a higher risk of getting colon cancer. They also have a higher risk of dying from colon cancer once they get it. If you’re overweight, losing just a little weight every year can reduce your risk of pre-cancerous polyps by almost 50%. Type 2 Diabetes is frequently a complication of being overweight. Type 2 Diabetes seems to be a risk factor for colon cancer. Many people who lose weight find that their Type 2 Diabetes goes into remission. So losing a few pounds may help reduce two different risk factors.
  • Alcohol use: People who drink a moderate (1 drink on most nights) or more, have a 20%-50% increased risk of developing colon cancer compared to people who don’t drink.
  • Tobacco use: Tobacco use and smoking is one of the major risk factors for developing colon cancer. The chemicals in tobacco are known to damage DNA in many types of cells. Quitting tobacco can reduce your risk for colon cancer and other diseases as well.

The Bottom Line:

Doctors don’t know exactly what causes colon cancer in individual patients. They do know that colon cancer, like all other cancers, can happen when DNA gets damaged and allows cells to grow out of control. They also know that certain risk factors increase our risk of developing colon cancer. Some of the risk factors are because of lifestyle choices we make and they can be changed. If you have risk factors, it’s especially important to get checked out with a screening test at the earliest possible time. Check it for someone you love. #CheckIt4Andretti.

Fast Facts:

  • Doctors can’t say exactly what causes colon cancer to happen in most people
  • Colon cancer develops when DNA in the cells of the large intestine are damaged
  • You can’t change your family history or age, but you may be able to change some of your “lifestyle” risk factors and possibly reduce your chance of developing colon cancer.
  • If you have risk factors, make sure to get checked for colon cancer at the right time. Screening tests such as colonoscopy can help find polyps and cancers early.

What Age are You Most Likely to Get Colon Cancer?

A lot of people want to know “the most likely age” a disease might happen. Getting screened, eating healthy, exercising and minimizing alcohol and tobacco can take some of the joy out of life. Especially if a disease might not strike until later in life. You might think of colon cancer as a disease of older people who have a lot of risk factors. But the truth is colon cancer can happen to anyone, even really young people.

What age can you get colon cancer?

The average age of being diagnosed with colon cancer is 68 for men and 72 for women. The “average age” is a little misleading and doesn’t tell the whole story. The average age at diagnosis has been getting younger for the past couple of decades, and doctors aren’t sure why. It could be because screening in older people is catching polyps before they have a chance to turn into cancer. Or it could be that there are more chemicals and toxins in the environment. Or maybe it’s because we’re more sedentary and eating more processed food at an earlier age.

Most cases of colon cancer still happens in people over 50 years old, but about 12% of cases are diagnosed in people under 50. Young men and women in their 20’s are diagnosed with colon cancer every year. As a matter of fact, the rate of people under 50 getting colon cancer has gone up about 2% a year since 1995. The rate for people over 50 has actually gone down about 3% a year during that same time. Screening tests like colonoscopies are thought to be one of the biggest reasons for the drop in those over 50.

So, who is most likely to get colon cancer?

Anyone can get colon cancer, but some people are more likely to get it than others. In an earlier blog post we talked about risk factors for getting colon cancer. It’s worth mentioning them again here, because they help us understand who is most likely to get colon cancer. A “risk factor” doesn’t cause cancer all by itself. Risk factors just mean that you have a greater chance of developing a disease than someone who doesn’t have them. Some people have lots of risk factors and never get cancer. Other people might not have any risk factors at all and still get that terrible diagnosis.

You have a greater chance of getting colon cancer if:

  • You are male: Men have about 30% higher rate of colon cancer than women.
  • You are Black or Native American/Alaskan: White Americans are about 30% less likely to be diagnosed with colon cancer than Black Americans. 
  • You are over 50 years old: The older you are, the higher your risk.
  • You have a lifestyle that puts you at risk; Obesity, smoking and alcohol overuse are all risk factors. So is being sedentary and eating a highly processed diet.
  • You have particular genetic syndromes: If colon cancer “runs in your family,” you may familial adenomatous polyposis or Lynch Syndrome. These are genetic conditions that are passed down through generations.
  • You have certain types of inflammatory bowel disease like Crohn’s or ulcerative colitis.

Can I still get colon cancer if I don’t have any symptoms or risk factors?

You might not be overweight. You may have never smoked or drank alcohol. You might even eat 5-7 servings of vegetables and walk 2 miles every day. But you could still get colon cancer. Risk factors are only part of the puzzle of who gets this disease. Genetics are part and so is the environment. Every day that you get older, your risk goes up a little bit, even if you try to do everything “right.”

It’s important to remember that many people don’t have any symptoms at all  in the early stages of colon cancer. In order to catch colon cancer before it gets too far along, you should start getting screened at age 45 according to national guidelines. If you have other risk factors, talk to your doctor about getting screened earlier.

No matter what your age is or whether you have risk factors, you need to talk to your doctor right away if you have any symptoms that go along with colon cancer. Things like blood in your stool, bloating, weight loss, abdominal pain or feelings of fullness in your belly might be nothing…but they could also be the first clues of colon cancer.

You can get an idea of your individual risk by using the National Cancer Institute’s Colorectal Cancer Risk Assessment Calculator. Just answer a few questions online and you can print out the assessment to take to your doctor. It’s an easy way to start a difficult discussion.

The bottom line:

It’s impossible to predict at what age someone will develop colon cancer, or whether they’ll ever get it. Some people have lots of risk factors and never develop the disease. The average age is getting younger for men and women, and you’re more at risk as you get older, especially if you’re male, Black or have other risk factors. Regular screening beginning at age 45, and up until age 75, is recommended for all Americans. Check it as soon as you turn 45. Check it for someone you love. Check it for yourself. #Checkit4Andretti.

Fast Facts:

  • The average age of being diagnosed with colon cancer is getting younger.
  • You’ll have a better chance of surviving colon cancer if you catch it early, before it spreads to other parts of the body.
  • Since it is impossible to know for sure who will get colon cancer, every American between the ages of 45-75 should be screened regularly.