Colorectal cancer is one of the commonest cancers in Hong Kong. Most colorectal cancers begin as a small polyp. Polyps are usually benign, but some may gradually develop into cancer. The development of a polyp into cancer may take more than 10 years. If not treated early, cancer cells may invade and damage nearby organs, they can also spread to other parts of the body via the bloodstream and lymphatic system.

Risk Factors

A number of risk factors for colorectal cancer are closely related to our lifestyle and dietary habits, and therefore modifiable. These include inadequate fibre intake, consumption of processed meat and excess red meat, lack of physical activity, obesity, alcohol consumption and smoking.

On the other hand, some risk factors cannot be modified:

• Men at or above the age of 50
• Having hereditary bowel diseases, e.g. familial adenomatous polyposis or Lynch Syndrome
• Persistent inflammation of the bowel, e.g. ulcerative colitis
• History of colonic polyps
• Family history of colorectal cancer, particularly in first-degree relatives (i.e. parents, siblings or children)
  
  • Risk would be even higher for individuals with one first degree relative diagnosed with colorectal cancer at or below 60 years of age, or more than one first degree relatives with colorectal cancer irrespective of age at diagnosis.

Signs and Symptoms

Common symptoms include:

• Change in bowel habit (diarrhoea or constipation) with unknown reason and lasting for more than two weeks
• Blood or a large amount of mucus in the stool
• Narrowing of stool
• Persistent urge or a feeling that the bowel doesn't empty all the way after passing stool
• Abdominal discomfort (persistent pain, bloating, fullness or cramps)
• Weight loss and tiredness with unknown reason

As these symptoms can be similar to the symptoms of other gastrointestinal diseases, you should consult a doctor as soon as possible if you develop any of the above symptoms.

Prevention of Colorectal Cancer

A healthy lifestyle can reduce the risk of developing colorectal cancer.

1. Consume more high-fibre food, e.g. whole-grains, beans, fruits and vegetables
2. Adopt a low fat diet
3. Use healthy cooking methods, e.g. steaming, blanching, baking, braising, stewing, etc.
4. Decrease consumption of red meat, e.g. beef, lamb and pork; and avoid consuming processed meat, e.g. ham, sausages, bacon and luncheon meat
5. Do adequate amount of physical activity regularly
6. Maintain an optimal body weight and waist circumference
7. Abstain from alcohol drinking and smoking

Colorectal Cancer Screening

There may be no apparent symptoms at early stage of colorectal cancer. The purpose of colorectal cancer screening is early identification of people who have the disease or at increased risk of it, before the symptoms arise, so that treatment could be commenced earlier.

The Cancer Expert Working Group on Cancer Prevention and Screening (CEWG) established by the Government recommends that people aged between 50 and 75 and at average risk should consult their doctors to consider one of the following screening methods:

1. Annual or biennial faecal occult blood test (FOBT); or
2. Sigmoidoscopy every 5 years; or
3. Colonoscopy every 10 years.

The Government-launched Colorectal Cancer Screening Programme subsidises eligible asymptomatic Hong Kong residents aged between 50 and 75 to undergo screening regularly for prevention of colorectal cancer. Under the programme, participants can receive a FOBT screening provided by an enrolled primary care doctor. If the test result is positive, the participant will need to be assessed by colonoscopy and therefore be referred to an enrolled colonoscopy specialist. If the result is negative, the participant is advised to repeat the screening two years later.

You may visit the website of the Colorectal Cancer Screening Programme for more details.

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