According to the American Cancer Society, 1 in 25 women (4.0%) and 1 in 23 men (4.3%) will develop colorectal cancer in the course of their lifetime. The Society estimates that there will be 104,270 new cases of colon cancer and 45,230 of rectal cancer in 2021. In the same year, this disease is expected to cause approximately 52,980 deaths in the United States.

Colorectal cancer affects the colon or the rectum, the final parts of the digestive tract. It usually originates from polyps, most commonly adenomatous polyps. These polyps are clusters of abnormal cells that become abnormal growths and may turn into cancerous cells at some point in time. They are relatively easy to spot during a routine colorectal cancer screening procedure.

The foundation of colon cancer prevention is colon cancer screenings along with lifestyle changes that will reduce some of the known risk factors for colon cancer.

Regular Screening

Screening describes the process of searching for precancer or cancer signs in people who have no symptoms of the disease. The goal of regular screening for any cancer (such as breast cancer, testicular cancer, cervical cancer, etc.) is to detect the cancerous changes as early as possible to increase the likelihood that they will respond to curative treatment. 

If discovered early enough, colon cancer has a 5-year survival rate of 91%. For rectal cancer, this percentage is 89%. 

Screening options for colorectal cancer includes two types of exams:

• Visual exams, the most common of which is colonoscopy

• Stool-based tests, or fecal testing, where stool is examined for signs of cancer

Visual Exams

During a colonoscopy, a gastroenterologist (doctor specializing in the digestive system) will insert a long, flexible tube with a camera at the tip (colonoscope) through the anus, rectum, and entire colon. The camera will allow them to get a look inside the intestines and spot any polyps or abnormalities that might be occurring.

As of yet, colonoscopy is one of the most reliable methods for detecting colorectal cancer. It is not pleasant, but it is necessary for every adult over the age of 45. If you are younger than 45 but have a high risk of colon cancer (such as a family history of the disease, personal history of polyps, an inherited cancer syndrome, or similar), you should start getting screened early.

Colorectal cancer screening should be performed at least every ten years. Your doctor will decide on the frequency based on your risk factors. 

Stool-Based Tests

Fecal tests are stool samples examined in a laboratory. They are far less invasive than a colonoscopy but also less reliable. Three main types of stool-based tests can be performed:

• Guaiac-based fecal occult blood test (gFOBT) – done once a year

• Fecal Immunochemical test (FIT) – also done once a year

• FIT-DNA test (stool DNA test) – done once every three years

If any of these tests are recommended by your doctor, and they show positive results, you will have to undergo a colonoscopy for diagnosis confirmation. 

Genetic Testing

Genetic tests are not necessary for everyone. If you have a family history of colorectal cancer,  who has been diagnosed, it might be a good idea to consult with a genetic expert.

While, genetic testing doesn’t provide clear-cut evidence of disease, it can rule out certain forms of inherited colorectal cancer including Lynch syndrome (hereditary nonpolyposis colorectal cancer, HNPCC) or familial adenomatous polyposis (FAP).

If you have genetic predispositions, screening earlier for colorectal cancer is generally recommended.

Lifestyle Changes

Specific lifestyle adjustments might drastically lower your risk of colon cancer. 

• Maintaining a healthy weight. A high BMI is a known risk factor for colorectal cancer. 
• Increasing physical activity. You might not have to join a gym or start doing CrossFit, but regular moderate to vigorous activity contributes to lower risks of colon cancer. Limiting your lying and sitting down time is also beneficial. Going for walks, swimming, riding a bike, hiking, yoga – anything counts!
• Consuming a well-balanced diet. In general, a healthy diet based on vegetables, fruits, and whole grains (such as brown rice) with little to no red and processed meats most likely lower the risk of colorectal cancer. However, experts are still unsure which aspects of this are the most important ones.
  Several studies have documented the connection between red meats (pork, lamb, and beef) and processed meats (lunch meats, hot dogs, sausages) and increased colon cancer risk.
  Previously, medical practitioners believed that a diet rich in fiber prevents colorectal cancer. Research has debunked this theory. A high fiber intake is good for digestive health and preventing heart disease and diabetes but has no bearing on colorectal cancer.
• Reducing alcohol intake. An increased alcohol consumption links to a higher risk of colon cancer. Not drinking any alcohol or limiting your alcohol intake as much as possible may lead to a lower risk of cancer. 
• Quitting smoking. Smoking is known to cause various forms of cancer, primarily lung cancer. It also contributes to the development of colorectal cancer. Quitting smoking helps lower the risk of different types of cancers, including colorectal. 

Supplements

Supplements have been recommended to help support a healthier digestive tract in hopes of preventing colorectal cancer. However, no supplement is 100% safe and should be taken with caution and under the professional guidance of a medical practitioner. 

• Vitamins. Scientific opinion on whether folic acid or folate helps in colorectal cancer prevention is divided. Some studies suggest that folic acid might aid the growth of certain tumors. 

Low vitamin D levels are associated with different cancers, as well as colorectal cancer. Vitamin D can be acquired from certain foods, sun exposure, and vitamin pills. Avoiding a low level of vitamin D might be beneficial. It is best to consult with your doctor about that.

• Calcium. The American Cancer Society does not offer any specific recommendations for calcium in terms of colon cancer. Increasing calcium might lower the risk for this type of cancer, but it increases the risk of prostate cancer in men.
• Non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs are drugs that reduce pain, fever, and inflammation. The most common ones are aspirin, ibuprofen (Advil, Motrin), and naproxen (Aleve). Many studies have discovered that patients who regularly take these drugs have a lower incidence of polyps and colorectal cancer.
  However, it is vital to mention that NSAIDs can cause serious side effects when taken in excess. They can trigger bleeding in the digestive tract and stomach ulcers which far outweigh the benefits of potentially preventing colorectal cancer.
  Before deciding to regularly take aspirin or a similar medication, make sure to check with your doctor.

Conclusion

Colorectal cancer prevention is largely focused on screening and lifestyle changes. Screening involves colonoscopy or stool-based tests (potentially followed by a colonoscopy) and genetic options for those with a family history of this disease.  Lifestyle changes involve eating healthy, reducing your body weight, increasing your levels of activity, and quitting smoking and alcohol use. Supplements are also employed although these decisions are best under the guidance of specialists.

While research has helped us to better understand carcinogenesis of the colon, we are far from implementing practices in standard care that can prevent and cure the disease. Many advances are on the horizon. Here’s how you can help speed up the research process.