DEAR MAYO CLINIC: I just turned 48, and although I am a bit overweight, I am in otherwise good health. At my recent annual checkup, I was asked about my family's colorectal cancer history. After sharing that my father had colon polyps removed at some point in his life, my doctor ordered a colonoscopy. I am wondering, why the rush to get a colonoscopy as I thought I wasn't at risk for cancer until later in life?

ANSWER: Colorectal cancer is a term that includes colon and rectal cancers, both of which originate in the lower portion of the large intestine and into the rectum. Estimates are that about 1 in 20 people in the U.S. will be diagnosed with colorectal cancer in their life. Men are slightly more likely than women to be diagnosed with colorectal cancer, and African Americans have a higher risk than people of other races.

What prompted your health care provider to recommend a colonoscopy is likely a combination of several things. First, you mentioned that your father had a colon polyp removed. A colon polyp is a precursor to cancer. Polyp development can be hereditary.

Screening seeks to identify precancerous polyps that may develop into cancer. If polyps are found early and removed, the cancer risk is reduced. Colon cancer is one of the only cancers that can be prevented with effective screening.

Colorectal cancer was once thought of as a disease of aging, as the risk for developing this cancer increases after 50. However, anyone is at risk.

Other factors that contribute to the development of colorectal cancer include:

• Family history.
• Inflammatory bowel disease.
• Diabetes.
• A low-fiber and high-fat diet.
• Radiation therapy for cancer.
• Hereditary colon cancer syndrome.

Another reason your health care provider may have suggested a colonoscopy for you is that over the past few decades there has been a growing trend of more young people developing colorectal cancer. In recent years, there has been an increase in colorectal cancer diagnoses in people 40 to 49, but half of young-onset colorectal cancer patients are under 40.

The U.S. Preventive Services Task Force drafted recommendations for screening in fall 2020 for certain populations to start at 45 — five years earlier than the previous recommendation.

I would recommend that you talk with your father and find out more about your family history. Is it just one or two colon polyps he had removed? Do you have other relatives who have been diagnosed with cancer?

Understanding a patient's family history helps with the type of screening performed. In some cases, your health care provider may try to discern if there is a hereditary condition ― the most common of which is Lynch syndrome. People who have Lynch syndrome have an inherited mutation in a gene that increases your risk of colon cancer, endometrial cancer and several other cancers involving the colon.

It is important to note that only about 20% of the people who develop early-onset or young-onset colon cancer will be found to have a hereditary type of genetic change. Most patients do not.

Research is still underway to determine the reason for the rise of colorectal cancer in young people. Some believe it may be related to changes in diet, increasing rates of obesity and decreased physical activity.

Take this opportunity to review your lifestyle. Diet and exercise can help prevent colorectal cancer, and contribute to overall good health. Focus on eating a diet rich in fruits and vegetables, and minimize the amount of red meat and processed meats like bacon and sausage that have nitrites. Reduce alcohol intake, avoid tobacco and increase physical activity.

Also, regardless of your age, be aware of the symptoms of colorectal cancer. These can include abdominal pain, change in normal bowel pattern, unexplained or unintended weight loss, blood in the stool, or dark tarry stools. Fatigue can result from blood leaking from the tumor and lead to anemia, which is a decrease in oxygen-carrying hemoglobin that is measured by a blood test.

The COVID-19 pandemic has profoundly affected cancer diagnoses and treatments. Colonoscopies, for instance, have decreased 90% over the past year. Though colonoscopies are the most effective, another option for colorectal cancer screening is Cologuard, an at-home test that Mayo Clinic helped develop.

I would encourage you to talk with your health care provider further if you have concerns, but don't delay screening. Colon cancer is the only cancer that is preventable. ― Compiled by Mayo Clinic staff

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Related Articles 

• Colorectal cancer cases rising in younger adults, screenings are down published 3/16/21
• Mayo Clinic Minute: What you should know about colorectal cancer published 3/3/21
• Mayo Clinic Q&A podcast: Screening for colorectal cancer can be prevention published 3/1/21
• Updated screening guidelines for colorectal cancer published 10/30/21

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