Colon Cancer


Colon cancer also called colorectal cancer, occurs when tumorous growths develop in the large intestines. It begins in the colon, which is the final part of the digestive tract, and may spread to other parts of the body if not managed early.

Colon cancer normally affects older people, although it can occur at any age. It is the third most common type of cancer in the US and the world at large after lung cancer and breast cancer, respectively.

It affects men and women equally. Colon cancer is also reported as the second leading cause of cancer deaths in the world. Black people are more vulnerable to colon cancer than whites and people of other races.

Most colon cancers develop from polyps, and thus, removal of the polyps can help in the prevention of the illness. Early diagnosis and treatment often lead to successful healing.

Colorectal cancer is the leading cause of cancer morbidity and mortality in the world with 1,849,518 new cases reported in 2018 of which 880,792 passed on.

In Kenya, the number of new colon cancer cases is estimated at 2,316 and 1,466 deaths reported in 2018. It is advisable to commence colorectal cancer screening at 45 to be on the safe side.


Most people with colon cancer do not exhibit signs and symptoms during the early stages. When the symptoms emerge, they include:

  • Change in bowel habits – constipation or diarrhea
  • Rectal bleeding
  • Persistent abdominal discomfort such as cramps or bloating
  • Abdominal pain
  • Tenesmus – the feeling of incomplete bowel emptying 
  • Weakness or fatigue
  • Unexplained weight loss
  • Intestinal obstruction
  • Iron-deficiency anemia


Doctors are not yet sure what causes colorectal cancers, but researchers are working on it.

Generally, cancer begins when healthy cells in the colon mutate (develop changes) in their DNA. The DNA of a cell contains instructions that tell a cell what to do.

When a cell’s DNA is damaged and becomes cancerous, it fails to tell the cell what to do, and the cells continue to multiply even when new cells are not needed. The more the cancerous cells accumulate, the more they are likely to develop a tumor.

If not detected early and treated, the cancer cells can grow to attack and damage the normal tissue surrounding the colon. The cancerous cells can also move to other parts of the body to form deposits – metastasis.

Risk Factors

The factors that may increase the risk of colorectal cancer include:

  • Older age: cancer can be diagnosed at any age, but most people with the condition are older than 50. However, the rates of colon cancer in younger people (less than 50) have been on the rise, although it is not clear why.
  • African race: Black people have a greater risk of colon cancer than individuals of other races.
  • Personal history of colon cancer or polyps: If you have had colon cancer or noncancerous colon polyps, you have a greater risk of colon cancer in the future.
  • Inflammatory intestinal conditions: Chronic inflammatory diseases of the colon that include Crohn’s disease and ulcerative colitis can increase the risk of colon cancer.
  • Inherited syndromes that increase colon cancer risk: Certain gene mutations passed through generations of the family can increase your risk of colon cancer.
  • Family history of colon cancer: You are at higher risk of developing colon cancer if you have a blood relative who has had the disease. If more than one family member has rectal cancer or colon cancer, your risk is even greater.
  • Low-fiber, high-fat diet
  • A sedentary lifestyle
  • Obesity
  • Diabetes
  • Smoking
  • Alcohol
  • Radiation therapy for cancer


The doctor will conduct a complete physical examination and ask you about personal and family medical histories.

Diagnosis is normally done after colonoscopy or a barium enema x-ray.

The colonoscope contains a long, flexible tube fitted with a camera on one end and inserted into the rectum to inspect the colon. The patient may be required to follow a special diet for one to two days to make the procedure possible.

The double-contrast barium enema is an x-ray procedure that employs liquid called barium to offer clearer imaging results than a standard x-ray can give.


There are several ways of staging cancer. The stages depend on how far cancer has spread. The following four-stages are common for colon cancer:

  • Stage 0: The cancer is in an early stage known as carcinoma in situ. It has not grown further than the inner layer of the colon.
  • Stage 1: cancer has grown into the next layer of tissue but has not spread to lymph nodes or other organs. 
  • Stage 2: cancer has spread to outer layers of the colon but has not gone beyond the colon.
  • Stage 3: cancer has grown and spread to outer layers of the colon and has reached about three lymph nodes. However, it has not grown to distant sites. 
  • Stage 4: cancer has spread to other tissues beyond the wall of the colon. As this stage progresses, cancer reaches distant parts of the body. 


There are various treatment options. They include:

  • Surgery: It is used to remove the tumor and the adjacent lymph nodes. It is recommended for early treatment for stages 0 to 2.
  • Chemotherapy: The treatment employs drugs to shrink or get rid of cancer cells. The option typically targets rapidly multiplying cells, which makes it ideal for treating cancer. However, it is also associated with a few side effects, such as nausea and weight loss.
  • Radiation therapy: It uses high-energy rays to kill cancerous cells. A doctor may equally use radiation to shrink a tumor before removing it surgically. It is a very useful approach for cancers that occur in one location and have not spread.
  • Targeted Therapy: It is the use of specific medications that target a particular behavior in cancer cells. They include medicines that stop cancer cells from multiplying.


Screening for colon cancer is recommended for individuals with an average risk, mostly those aged about 50 years.

However, those with increased risk, such as those with a family history of the condition are advised to consider screening sooner.

Other preventive measures are generally lifestyle changes that include:

For more information on treatment, speak to a doctor, or get access to a hospital near you through the Uzima Health App.