Colon Cancer: Causes, Symptoms, Prevention and Treatment

Colorectal cancer, or bowel cancer, is the second most common cancer in Hong Kong, according to the Department of Health. Over 2000 people are diagnosed with bowel cancer each year. Sadly, the number of new bowel cancer cases is showing no sign of slowing down.

The early symptoms of colorectal cancer can be subtle; nevertheless, this type of cancer is highly preventable, and curable if detected early. Be aware of some early symptoms of colon cancer and start regular colorectal cancer screening early can significantly increase the chances of successful treatment.

Causes of colorectal cancer

The exact cause of colorectal cancer is not known; however, below are several risk factors closely linked to this type of cancer.

1. Diet: unhealthy high-fat and low-fibre diet can increase the risk of developing colorectal cancer.
   
   
2. Lifestyle: heavy alcohol use, tobacco smoking and lack of exercise.
   
   
3. Family history: People with a family history of colorectal cancer also have a high risk of developing the disease.

Signs and symptoms of colon cancer

Colorectal cancer may not show any signs or symptoms in the early stages, but you may want to seek medical attention should one or more of the following symptoms occur:

• Blood in stool
• A change in usual bowel habit, e.g. constipation, diarrhoea
• Unexpected weight loss
• Tiredness
• Abdominal pain or discomfort

Colon cancer stages

Stage 0 indicates the earliest stage of colorectal cancer which then ranges from stages 1 through 4. The lower the number, the less the cancer has spread, and greater the survival rate, according to a HKU medical research.

Stage 0

• This stage is also called carcinoma in situ. It’s restricted to the innermost lining of the colon.
  
  

Stage 1

• The cancer cells begin to spread but are still in the inner lining.
• 5-year relative survival rate: >90%
  
  

Stage 2

• The tumour may extend into nearby tissue, but not yet spread to the lymph nodes.
• 5-year relative survival rate: 55-70%
  
  

Stage 3

• Cancer has spread to lymph nodes, but not yet to other parts of the body.
• 5-year relative survival rate: 25-55%
  
  

Stage 4

• Cancer has been carried through the lymph system to other parts of the body; commonly lungs and liver.
• This is known as metastasis.
• 5-year relative survival rate: 8%

Colon cancer prevention

1. Colorectal Screenings - Colorectal screenings examine the inside of the colon and rectum and can detect polyp growths which can be removed before they turn cancerous. The recommended age to start colorectal screening is 45, but people with a family history of colorectal cancer should start at a younger age. Speak to your doctor about when to start your screening.
   
   
2. Diet - Vegetables, fruits and whole grains are associated with a lower risk of colorectal cancer. Meanwhile, red meat and processed meats, e.g. luncheon meats, are linked with a higher risk.
   
   
3. Exercise - Regular exercise stimulates bowel movement and helps control weight, lowering the risk of colorectal cancer.
   
   
4. Cigarettes and Alcohol - Smoking and high alcohol consumption are believed to increase the risk of colorectal cancer.  The American Cancer Society recommends that people limit alcohol consumption to two drinks a day for men and one drink per day for women.

Treatments for colon cancer

Colorectal cancer is usually treated by  - 

• Surgery
• Chemotherapy 
• Radiation therapy

or a combination of the above methods.

Doctors will determine the most suitable treatment according to the type of colorectal cancer, its size and position. Other factors, such as possible side-effects of the treatment and the health conditions of the patient will also be considered.

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Sources:

1. Department of Health, HKSAR Government- Colorectal Cancer
2. American Cancer Society - Cancer Signs and Symptoms
3. American Cancer Society - Six Ways to Lower Your Risk for Colorectal Cancer
4. CCAlliance - Colorectal Cancer Stages 
5. Cancer center - Colorectal Cancer Risk Factors