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Certain factors can increase the risk of developing rectal cancer, including:

• Age: Most cases happen in people over 50, with the average diagnosis at 63, though there is a concerning trend of colorectal cancer diagnoses in younger people.
• Family History: Having a close relative with rectal or colon cancer nearly doubles the risk.
• Diet: Eating a lot of red or processed meat and not enough vegetables may increase the risk.
• Alcohol Use: Heavy drinking has been linked to a higher chance of colorectal cancer.
• Obesity: People with obesity are more likely to develop rectal cancer.
• Lack of Physical Activity: Being inactive may raise the risk, while regular exercise can help lower it.
• Smoking: Smoking increases the chances of dying from rectal cancer.
• Type 2 Diabetes: People with diabetes may be more likely to develop rectal cancer.
• History of Polyps: Past colon or rectal polyps can increase the chance of cancer.
• Inflammatory Bowel Disease: Conditions like and can increase risk.
• Certain Genetic Conditions: Inherited syndromes like Lynch syndrome and can raise the likelihood of developing rectal cancer.
• Previous Cancer: People who have had cancer of the colon, rectum, ovary, endometrium, or breast may be at higher risk.
• Radiation Exposure: Radiation therapy to the abdomen for past cancers may make rectal cancer more likely.
• Race: Studies show that Black individuals are more likely to develop rectal cancer, though the reasons aren’t fully understood.
• Sex: Men are slightly more likely to develop rectal cancer than women.

Although rectal cancer cannot always be prevented, certain lifestyle choices can help lower the risk. Maintaining a healthy weight, staying active, and eating a balanced diet with lean protein, whole grains, and plenty of vegetables while avoiding processed meats are all beneficial. Limiting alcohol and avoiding tobacco use can also reduce the risk. Most importantly, regular screenings can detect precancerous polyps early, decreasing the chances of cancer developing.

Rectal Cancer Screening 

Knowing your risk for rectal cancer can help you determine when you should begin screening. Risk factors are things that can increase your chance of developing the disease.

If you're 45 or older, have no symptoms, and have no family history of rectal cancer or growths (polyps) in your colon or rectum, you are considered to be at average risk. However, if you have family members who have had rectal cancer, or if you've had polyps or inherited conditions like Lynch Syndrome or familial adenomatous polyposis (FAP), you may be at a higher risk. If this is the case, it’s important to talk to your healthcare provider about starting screenings earlier.

Screening is recommended until age 75. After that, it depends on overall health and doctor recommendations. Screening is not advised after age 85. However, if you have had a large polyp or colorectal cancer in the past, you likely will have a more frequent surveillance schedule that goes beyond the typical screening recommendations. 

Types of Screening Tests

• Colonoscopy: (Every 10 years or depending on your physician’s instructions.) A doctor examines the colon with a thin, flexible tube and removes any polyps before they turn into cancer.
•  (Every 3 years.)These detect signs of cancer in stool and include FIT and gFOBT (both done yearly) and stool DNA tests.
• Other visual exams: CT colonography, also known as — a computer assisted approach that is less invasive than traditional colonoscopy— and sigmoidoscopy (both done every 5 years) offer alternative screening options.

When and Why Doctors Recommend Stool-Based Tests vs. a Colonoscopy

For people at average risk of colorectal cancer, doctors may recommend starting with a stool-based test. These at-home tests check for hidden blood or changes in DNA in the stool that could be signs of cancer or precancerous polyps. They are noninvasive and can help determine whether further testing, like a colonoscopy, is needed. A positive result means a colonoscopy is necessary. A negative result may allow someone to delay colonoscopy, depending on their doctor’s advice.

Stool-based tests are only appropriate for those who have no symptoms and no personal or family history of colorectal cancer, polyps (adenomas), or inherited cancer syndromes. People at higher risk should begin screening with a colonoscopy, which is the most accurate method and the gold standard for detecting colon or rectal cancer.

Doctors may suggest a stool-based test starting at age 45, but it can also be considered at any age if the person is symptom-free and at average risk. It may also be an option for someone older who has never been screened, or for someone who had a negative colonoscopy in the past and prefers a noninvasive way to check if a repeat colonoscopy is needed. 

Genetic Counseling and Prevention

For those with a strong family history, genetic counseling can help assess risk and create a personalized prevention plan. Experts at Dana-Farber Brigham’s offer evaluations and guidance to help manage cancer risk.