DEAR MAYO CLINIC: A friend was just diagnosed with colorectal cancer. She's only 30. I didn't know young people could get this cancer. Can you tell me more about it?

ANSWER: Unfortunately, your friend is among a growing number of adults under 50 who are being diagnosed with colorectal cancer. Many younger adults don't consider themselves at risk, since screening for colorectal cancer typically doesn't start until age 45.

That's why it's especially important to know the warning signs of colorectal cancer and not put off getting medical attention. Early diagnosis is essential to surviving colorectal cancer. If this cancer is found when it's only in the colon or rectum, the five-year survival rate is over 90%. That survival rate drops to roughly 15% if the cancer spreads beyond the colon and rectum.

 What is colorectal cancer?

It's not one type of cancer but two: colon and rectal cancer. The large intestine has several regions. The last part of the large intestine is known as the rectum. The other areas of the large intestine are called the colon. The treatments for cancers of the colon and rectum are different.

Who is at risk for this cancer?

Risk factors for colorectal cancer include:

• Older age
• Black race 
• Low-fiber, high-fat diet 
• Not exercising regularly
• Diabetes 
• Obesity 
• Smoking
• Drinking alcohol 

Those who are at higher risk for colorectal cancer tend to have at least one of these factors:

• Medical condition that places them at higher risk.
• Genetic condition that increases their risk. 
• Family history that places them at higher risk. For example, this is could be a first-degree family member such as parents or siblings who have had a diagnosis of colorectal cancer or advanced polyps.

Are there warning signs?

Four warning signs of colorectal cancer are:

• Abdominal pain
• Rectal bleeding
• Diarrhea
• Iron deficiency anemia

Although these symptoms can be embarrassing, you need to share them with a healthcare professional — don't put it off.

You may not easily notice blood loss after bowel movements, but that bleeding can lead to low iron levels. If a routine blood test reveals iron deficiency in a young adult, it can prompt the primary care clinician to consider colorectal cancer.

What is the screening process for colorectal cancer?

Your primary healthcare professional may order a screening that can help detect colon polyps or cancer. These tests include:

Stool DNA test. This test uses a stool sample to look for changes in cells' genetic material. Certain DNA changes are a sign that cancer is present or that it might happen in the future. The stool DNA test also looks for hidden blood in the stool.

If your stool DNA test returns positive (abnormal), you'll need a follow-up colonoscopy.

Colonoscopy. This test looks inside the colon. For it to be most effective, you need to thoroughly cleanse your colon, which involves reducing the fiber in your diet. The last step is consuming a special solution to ensure your colon is clean so the gastroenterologist is able to get a clear view. Although preparing for the procedure can be unpleasant, your care team can provide tips to make it more doable.

If the gastroenterologist finds any precancerous growths, called polyps, these will be removed during the colonoscopy and sent for testing. The number, size and type of polyps removed help determine when the next colonoscopy should be scheduled. If cancer is found, your care team will discuss treatment options with you.

How can I reduce my risk for colorectal cancer?  

No matter your age, there are five steps you can take to avoid developing colon cancer:

1. Eat your vegetables and healthy fats. Research has shown that the Western diet correlates to higher colorectal cancer rates. People who eat high-fiber diets are less likely to develop the disease.
2. Get moving. Exercise benefits your heart and helps you maintain your weight. It also can lower your colon cancer risk. Aim for 30 minutes of moderate exercise on most days of the week.
3. Watch your weight. Talk to your health care team if you need help losing weight.
4. Limit alcohol and don't smoke. If you choose to drink alcohol, do so moderately. That means no more than one drink a day for women or two drinks a day for men. And if you smoke, quit.
5. Follow colorectal cancer screening guidelines.

Derek Ebner, M.D., Gastroenterology, Mayo Clinic in Rochester

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