Stephan Thomé, M.D.
Hematology (Blood), Oncology (Cancer)
Colorectal cancer ― the third most commonly diagnosed cancer in the U.S. ― will account for nearly 53,000 deaths in 2021, according to the American Cancer Society. Yet prevention is possible when combining proper screenings, healthy lifestyle changes and increased awareness.
Learn more in this Q&A.
Q. What is colorectal cancer?
Colorectal cancer is an umbrella term used for cancer of the large intestine (colon), which is the lower part of your digestive system, and rectal cancer, which occurs in the last several inches of your colon. Cancer of the large intestine and cancer in the lower colon, or rectum, will be found in approximately 150,000 Americans and 45,000 Americans, respectively, in 2021. More than 1.5 million Americans are alive after a diagnosis of colorectal cancer.
How does colorectal cancer begin?
Most often, colorectal cancer starts with precancerous polyps in the lining of the colon. These precancerous cells can form in the shape of a mushroom, lie flat or be embedded in the colon walls. Finding and removing the polyps helps prevent colorectal cancer.
Does genetics play a role in colorectal cancer?
Most colorectal cancer is found in people without a family history of colon cancer. People with a family history have an increased risk of developing the disease, but it is not the only risk factor that should be considered when assessing individual risk.
A few factors put you at an increased risk for colorectal cancer:
Most people diagnosed with colorectal cancer are over 50. However, colorectal cancer affects young people, as well, albeit less frequently. A recent study suggests a small increase of colon cancer in U.S. adults under 40. This increase amounts to about 2% of the annual rates over the past decades. Given this increase, the recommended age for a person's first colon cancer screening has been lowered from 50 to 45.
African Americans are more susceptible to colorectal cancer than other races. Both African Americans, and Native Americans and Alaska Natives over 45 are at a higher risk, as well.
- Personal and family history
Previously having colorectal cancer, polyps or family history of the disease heightens colorectal cancer risk.
- Intestinal conditions
Preexisting inflammatory bowel diseases like ulcerative colitis and Crohn's disease increase the chance you'll develop colorectal cancer.
- Health problems and unhealthy lifestyle
Health conditions, such as diabetes and obesity, and unhealthy lifestyle decisions, such as lack of exercise, a diet high in fat, as well as smoking and heavy alcohol consumption, contribute to colorectal cancer. The rise of colorectal cancer in younger American adults has been linked to these modifiable risk factors, such as changes in diet and activity.
Can you prevent colorectal cancer?
The overall lifetime risk of colorectal cancer is 1 in 23 for men and 1 in 25 for women. While you can't completely eliminate all risk factors, like age, you can take steps to reduce your personal risk by making changes in your everyday life.
These steps will reduce your risk of developing colorectal cancer:
- Eat a variety of fruits, vegetables and whole grains.
Fruits, vegetables and whole grains contain vitamins, minerals, fiber and antioxidants that may play a role in cancer prevention. Choose a variety of fruits and vegetables so that you get an array of vitamins and nutrients.
- Drink alcohol in moderation, if at all.
If you choose to drink alcohol, limit the amount of alcohol you drink to no more than one drink a day for women and two for men.
- Stop smoking.
Talk to your health care provider about ways to quit that may work for you.
- Exercise most days of the week.
Try to get at least 30 minutes of exercise on most days. If you've been inactive, start slowly and build up gradually to 30 minutes. Also, talk to your health care provider before starting any exercise program.
- Maintain a healthy weight.
If you are at a healthy weight, work to maintain your weight by combining a healthy diet with daily exercise. If you need to lose weight, ask your health care provider about healthy ways to achieve your goal. Aim to lose weight slowly by increasing the amount of exercise you get and reducing the number of calories you eat.
If you have been diagnosed with an advanced colon polyp, talk with your health care provider about taking preventive aspirin. The U.S. Preventive Services Task Force concluded that aspirin reduces the risk of colorectal cancer by 40% in patients with advanced colorectal polyps. It is not recommended for everyone, so be sure to follow your health care provider's recommendations.
How is colorectal cancer diagnosed?
Colon cancer screening is of paramount importance for preventing and catching colorectal cancer early. Although a colonoscopy isn't perceived as the most glamorous screening, the benefits far outweigh the downfalls. Experts recommend that patients should begin colon screening at 45 or 10 years prior to when an immediate family member was diagnosed with colon cancer. For example, if your mother was diagnosed with colon cancer at 48, have your first screening at 38.
An alternative to a traditional colonoscopy is a new at-home test that Mayo Clinic helped develop. This test uses a stool sample to detect cancerous DNA. Talk to your health care provider to see if this may be an option for you.
This test requires no bowel preparation and no time off work, and it is covered by most health insurance plans as a colon cancer screening. It detects polyps and cancer. If abnormal, a follow-up colonoscopy is recommended to determine the source of cancerous DNA detected in the stool. Most tests will be negative, which will reduce the need for routine screening colonoscopies.
What are the symptoms?
Symptoms are usually subtle, if at all noticeable, during the early stages of colorectal cancer, which is why regular screening is vital.
If signs appear, they're usually in the form of:
- Blood in your stool or rectal bleeding.
- Unexplained weight loss.
- Persistent abdominal issues, including cramps, gas and pain.
- Persistent changes in bowel movements, including diarrhea, constipation or stool consistency.
- Fatigue or weakness.
- A feeling that your bowel doesn't empty completely.
Can colorectal cancer spread to other areas of the body?
Yes, colorectal cancer can spread to other areas of your body, most commonly to the liver. It can spread to your lungs, brain or lymph nodes, as well. It is more difficult to treat after it spreads. That's why it is so important to detect and diagnose it as soon as possible.
How is colorectal cancer treated?
Colorectal cancer treatments are more effective if the cancer is discovered early. Which treatments are most likely to help you depends on your particular situation, including the location of your cancer, its stage and your other health concerns. Treatment for colon cancer usually involves surgery to remove the cancer. Other treatments, such as radiation therapy and chemotherapy, also may be recommended.
What is the survival rate of colorectal cancer?
The bad news is that colorectal cancer is the third leading cause of cancer-related deaths in men and women. It is expected to cause about 53,000 deaths in 2021. The good news is that the death rate has been dropping for decades due to increased screenings, removal of polyps earlier and improvements in treatments.
The relative survival rate of any cancer compares people with the same type and stage of cancer to people in the overall population. The relative survival rate for colorectal cancer varies based on the stage of the cancer. According to the American Cancer Society, colorectal cancer that has not spread outside the colon or rectum has a five-year relative survival rate of nearly 90%; whereas, cancer that has spread to other are of the body is 14%–16%.
Colorectal cancer can be prevented with proper screening in concert with healthy lifestyle changes and increased awareness. Talk to your health care team if you have questions or concerns regarding colorectal health. And be sure to encourage your friends and loved ones to follow screening guidelines.