A quick and crucial Q&A on colorectal cancer


Listen to your gut – not just when you are trying to make a big decision, but more importantly when it comes to your general health.

Colorectal cancer, also known as bowel cancer, is the second most common cancer in men after prostate cancer and the third most common in women, surpassed only by breast and cervical cancer. 

As March is Colorectal Cancer Awareness Month, it’s the perfect time to take a deep dive into this dread disease and understand the basics to make sure you are informed. We asked Merck a couple of key questions to better understand colorectal cancer:


  • Why is it called colorectal cancer? 

The colon and rectum are connected and make up the large intestine, which is all part of the digestive system, therefore it’s called colorectal cancer.


  • What are the risk factors for colorectal cancer?

Lifestyle: Smoking and drinking alcohol can both increase the risk of bowel cancer.

Age: Colorectal cancer is generally seen in people over the age of 50. The risk of having the disease increases with age.

Bowel disease: If you already have bowel problems and suffer from inflammatory bowel disease (IBD), you have a higher risk of developing bowel cancer than the general population. 

Genetics: There are some rare-inherited conditions or syndromes associated with certain gene changes. Family members have an increased risk of bowel cancer if they inherit these gene changes and if they are a blood relative of someone with the disease.

Being overweight: Maintaining a healthy bodyweight, being active and eating a diet rich in vegetables, fruits and whole grains are all factors that will reduce your risk of colorectal cancer. Also try to stay away from eating too much red meat and processed meats.


  • How does colorectal cancer start?

Most colorectal cancers start as a growth, called a polyp, on the inner lining of the colon or rectum. Certain types of polyps may change into cancer over time, but this usually occurs after many years. Cancer is when abnormal cells start to divide and grow in an uncontrolled way. The cells can grow into surrounding tissues or organs and may spread to other areas of the body.


  • What are the symptoms?

People with colorectal cancer may not experience symptoms in the early stages. When symptoms appear, they usually vary, depending on the cancer’s size and location in the large intestine.

Common symptoms may include:

  • A change in bowel habit, such as diarrhoea, constipation, or smaller, more frequent bowel movements.
  • A change in appearance of bowel movements i.e., narrower stools or mucus in stools.
  • A feeling of fullness or bloating in the abdomen or a strange sensation in the rectum, often during bowel movement.
  • A feeling that the bowel hasn’t emptied completely.
  • Blood in the stools or on the toilet paper.
  • Unexplained weight loss.
  • Weakness or fatigue.
  • Rectal or anal pain.
  • A lump in the rectum or anus.
  • Abdominal pain or swelling.
  • A low red blood cell count (anaemia), which can cause tiredness and weakness.


  • Can colorectal cancer be treated successfully?

Going for regular screening is the best way to have peace of mind. If you experience any signs or symptoms of colorectal cancer, you should consult your doctor. A colonoscopy is a procedure where a fibre-optic camera is inserted through the anus in order to examine the colon. If colorectal cancer is suspected, a biopsy of abnormal tissue will be obtained during a colonoscopy.

Treatment will depend on how far the cancer has advanced and may include surgery, radiation, and chemotherapy, or a combination of these.

Early detection is key. If the cancer is diagnosed at a localised stage, the survival rate is 91%. If the cancer has spread to surrounding tissues or organs and/or the regional lymph nodes, the five-year survival rate is 72%. When colorectal cancer has already spread to distant sites by the time it is diagnosed, it is referred to as metastatic (stage IV) colorectal cancer, and the five-year survival rate is 14%.



  1. The Cancer Association of South Africa (CANSA). Colorectal Cancer. [Feb 2023]. Available at: https://cansa.org.za/colorectal-cancer/
  2. Cancer.Net. Colorectal Cancer Statistics. [Feb 2023]. Available at: https://www.cancer.net/cancer-types/colorectal-cancer/statistics#:~:text=rate%20is%2091%25.-,If%20the%20cancer%20has%20spread%20to%20surrounding%20tissues%20or%20organs,rate%20for%20people%20is%2067%25
  3. American Cancer Society. About Colorectal Cancer. [Feb 2023]. Available at: https://www.cancer.org/cancer/colon-rectal-cancer.html
  4. Cancer Council. Understanding bowel cancer: a guide for people with cancer, their families and friends. January 2019 Edition. Available at www.cancer.org.au.

5. Cancer Research UK. Bowel cancer risk factors. . [Feb 2023]. Available at: https://www.cancerresearchuk.org/about-cancer/bowel-cancer/risks-causes