Colorectal Cancer

  • It begins in the large intestine/colon.
  • The colon is the final part of digestive tract.
  • Colon cancer typically affects older adults, though can happen at any age.
  • It affects men and women equally and people of all races and nationalities.
  • It develops slowly over a period of 10 – 15 years.


Colorectal Cancer is the 4thmost common cancer in South Africa and 6thmost lethal.

Signs and Symptoms

Many people do not experience symptoms in the early stages of the disease.

When symptoms appear, they will vary depending on the cancer’s size and/or location in large intestines.

Symptoms include:

  • Persistent change in bowel habits:
    • Diarrhoea / constipation / change in consistency of your stool.
    • Loose / narrow stools.
  • Rectal bleeding/ blood in stool.
  • Persistent abdominal discomfort:
    • Cramps/ gas/ pain/ bloating.
  • Feeling that your bowel doesn’t empty completely.
  • Weakness/ fatigue.
  • Unexplained weight loss.
  • Pain during bowel movements.
  • Continual urges to defecate.
  • Irritable bowel syndrome (IBS)
  • Iron deficiency (Anaemia)

If cancer spreads to new locations in the body, additional symptoms can occur in the new area.

The liver is most commonly affected as well.


Physician carries out a complete physical exam and will ask about personal and family medical histories.

Diagnosis is usually made after a colonoscopy/ barium enema x-ray.

  • Colonoscopy:
    • Long, flexible tube with a camera on one end is inserted into rectum to inspect inside of colon.
    • Patients follow a special diet for 24 – 48 hours before procedure.
    • The colon requires cleansing with strong laxatives.
      • This process known as bowel prep.
    • If polyps are found in the colon, they are removed and sent to a pathologist for a biopsy.
      • This entails the examination of the sample under a microscope which detects cancerous/ precancerous cells.
    • A similar procedure examines smaller portion of colorectal area:
      • This is called flexible sigmoidoscopy and involves less preparation.
  • Double-contrast barium enema:
    • This involves an X-ray procedure that uses a liquid called barium to provide clearer imaging results than a standard x-ray.
    • Before the procedure, patients must fast for several hours.
    • A liquid solution containing the element barium is injected into colon through the rectum, followed by the brief pumping of air to smooth over the barium layer.
    • An X-ray of the colon and rectum is then taken.
    • Barium will appear white on the x-ray, tumours and polyps appear as dark outlines.
    • If the biopsy suggests colon cancer, the doctor may order chest x-rays, ultrasounds, CT scans of lungs, liver and abdomen to assess spread of cancer.
    • It may involve blood tests to test for a substance produced by some cancer cells called Carcinoembryonic antigen (CEA)

Risk Factors

  • Older age:
    • A person can be diagnosed at any age, but majority of people with colon cancer are older than 50.
  • Personal history of colorectal cancer/ polyps:
    • If you’ve already had colon cancer/ noncancerous colon polyps, you have a greater risk of colon cancer in the future.
  • Inflammatory intestinal conditions:
    • Chronic inflammatory diseases of the colon like Ulcerative colitis/ Chron’s disease can increase risk of colon cancer.
  • Inherited syndromes that increase colon cancer risk:
    • Some gene mutations passed through generations of your family can increase your risk of colon cancer significantly.
    • There is a small percentage of colon cancers linked to inherited genes.
    • The most common syndromes that increase colon cancer risk are familial adenomatous polyposis (FAP) and Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC).
  • Family history of colon cancer:
    • A person is more likely to develop colon cancer if they have a blood relative who has the disease.
    • If more than one family member has colon cancer, the risk is greater.
  • Diet:
    • A low fibre and high fat diet, as well as a diet high in red meats, can increase the risk of colon cancer.
  • A sedentary lifestyle:
    • People who are inactive are more likely to develop colon cancer.
    • Getting regular physical activity may reduce the risks of colon cancer.
  • Diabetes:
    • People with diabetes/ insulin resistance have an increased risk of colon cancer.
  • Obesity:
    • People with obesity have an increased risk of colon cancer.
  • Smoking:
    • People who have smoked tobacco for a long time are more likely than non-smokers to develop colon cancer.
  • Alcohol:
    • Heavy use of alcohol can increase your risk of colon cancer.
  • Radiation therapy:
    • Radiation therapy directed at the abdomen to treat previous cancers can increase your risk of colon cancer.


Treatment depends on the type and stage of cancer, as well as the age, health status and other characteristics of patient.

There is no single treatment, but the most common options are:

  • Surgery
    • Surgery to remove part of colon is called a colectomy.
    • It removes part of colon containing cancer as well as the surrounding areas.
    • Nearby lymph nodes are usually removed.
    • A healthy portion of colon will either be reattached to the rectum or attached to a stoma depending on extent of colectomy:
      • A stoma is an opening made in wall of abdomen.
      • Waste passes into a bag, removing the need for the lower part of the colon.
      • This is called a colostomy.
    • Small, localised cancers can be removed using an endoscopy.
    • Laparoscopic surgery uses several small incisions in the abdomen to remove larger polyps.
    • Palliative surgery may relieve symptoms in cases of untreatable or advanced cancers:
      • The aim is to remove any blockage of the colon and manage pain, bleeding, other symptoms.
  • Chemotherapy
    • This treatment administers chemicals that interfere with the cell division process by damaging proteins or DNA to kill cancer cells.
    • This treatment targets any rapidly dividing cells, including healthy ones.
    • Healthy cells can recover from any chemically-induced damage, but cancer cells not.
    • Chemotherapy is generally used to treat cancer that has spread because it travels through whole body
      • Treatment occurs in cycles so that the body has time to heal between doses.
  • Radiation
    • Radiation treatment damages and kills cancer cells by focusing high-energy gamma-rays on them.
    • Radioactive gamma-rays are emitted from metals such as radium, or from high-energy x-rays.
    • It can be used as a standalone treatment to shrink tumour and destroy cancer cells.
    • It can also be used alongside other cancer treatments.
    • It is usually only used at a later stage.