• Diet may be a factor. Risk seems to increase with diets low in fibre, fruit and vegetables and high in meats and fats. Risk seems to decrease with diets high in fibre and low in fats and red meat / processed meat.
• What increases the risk of colon and rectal cancers:
• Polyps or adenomas in the colon may become malignant. Polyps should always be removed and tested to see if they contain cancer. Most polyps do not contain cancer, but if left in place may develop into cancer.
• One in a hundred patients has a family background of polyps.
• Gender does not affect the occurence of familial polyposis (Gardner's Syndrome) [see note, Statistics]. Children of an affected parent have a 50% chance of inheriting the syndrome.
  
• A family history of colorectal cancer increases risk. The number of relatives affected, and their age when their cancer was diagnosed are important in estimating risk. We have a Hereditary Cancer Program in B.C.
• People with inflammatory bowel disease (ulcerative colitis, Crohn's disease) have an increased risk of developing colon cancer. This risk increases for patients who developed colitis at an early age.
• Use of alcohol, especially in men (two (2) or more drinks per day) [see note, Statistics]
  
• Body fatness / abdominal fatness
• Low physical activity levels
• Rectal cancer can recur (come back) more often than colon cancer. Close follow-up is necessary for these patients, and improves the possibility of cure.
• Statistics
  ^{NOTE:  Available statistics do not have information about the inclusion of transgender and gender diverse participants. It is unknown how these statistics apply to transgender and gender diverse people.  Patients are advised to speak with their primary care provider or specialists about their individual considerations and recommendations.}
  
• BC
  
• Canada

Can I help to prevent it?

Research shows that about 50% of colorectal cancers can be prevented by following a healthy lifestyle. This includes:

• People with moderate to high levels of physical activity have a lower rate of colon and rectal cancers. The evidence of benefit is stronger for colon cancer than for rectal cancer. Visit BC Cancer's Prevention page on Exercise Support for information and resources.
  
• Early detection of colon cancer through screening (see below).
  
• Eating healthy, nutritious foods can reduce your cancer risk. Follow the recommendations in Canada's Food Guide and cisit BC Cancer's Prevention page on Nutrition information and resources. The following steps may also be helpful for preventing colorectal cancers: 
  

  - Eat foods high in dietary fibre
  - Include unprocessed garlic in your meals
  - Include milk in your diet
  - If you choose to drink alcohol, the key is to keep your drinking at the safest possible levels, called low-risk drinking.
  - Limit your intake of red meat and processed meat.

Screening for this cancer

• The provincial Colon Screening Program is an organized population-based program aimed at reducing colon cancer incidence and mortality by promoting the early detection and prevention of colon cancer. 
  
• Doctors of B.C. (formerly the B.C. Medical Association) has developed provincial screening guidelines for colon cancer. The patient guideline is available, as well as the health professional guideline.
  
• In the general population, screening is recommended to start at age 50. All people aged 50-74 should receive both of these tests:
• annual digital rectal examination (DRE)
• a fecal occult blood test, called FIT (Fecal Immunochemical Test). This is a test looking for hidden blood in the feces, that can't be seen with the eye. Fecal occult blood tests can reduce mortality from colorectal cancer by 25% - 45%.
  
• The fecal occult blood test is a simple test performed by examining a stool (feces) sample for evidence of bleeding. Unfortunately it does have a high false positive rate for conditions other than cancer, such as: inflammation of the colon, peptic ulcer and hemorrhoids. Even the eating of rare meat or vigorous tooth brushing may produce a false positive result.
• If you can see blood in your stool, you do not need to do this test. This test is only to check for hidden blood. If you find blood in your stool, contact your doctor.
• Individuals at higher risk should have more frequent, more thorough examinations beginning at a younger age. The screening guidelines above will help you and your doctor decide on the best plan for you.

Signs and Symptoms

• A change in your bowel habits:
• bowel obstruction
• stool size change
• constipation
• diarrhea
• Blood in the stool, either apparent (visible) or occult (hidden)
• Lower abdominal pain or pelvic pain
• If the tumour has spread, it may result in enlargement of the liver, abdominal bloating, pain in lower back or bladder symptoms such as urinary frequency or blood in the urine.
• One in twenty patients may develop sudden obstruction of the bowel or a perforation (tear)
• Anemia
• Feeling very tired
• Nausea or vomiting
• Weight loss and weakness