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

Risk factors for colorectal cancer include low fibre intake, high consumption of red meat and processed meat, lack of physical activity, obesity, alcohol consumption and smoking. Individuals with the following risk factors are more prone to developing colorectal cancer:

• 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).

Signs and Symptoms

Early colorectal cancer may have no symptoms.

Common symptoms include:

• Change in bowel habits (diarrhoea or constipation) with unknown reason and lasting for more than two weeks
• Blood or a large amount of mucus in the stool
• Persistent urge 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 prevent or reduce the risk of developing colorectal cancer.

1. Eat more food rich in fibre, such as whole-grains, beans, fruits and vegetables
2. Decrease consumption of red meat and processed meat
3. Do adequate amount of physical activity
4. Maintain healthy body weight and waist circumference
5. Abstain from alcohol drinking and smoking

Colorectal Cancer Screening

The purpose of colorectal cancer screening is to identify people who have colorectal cancer or people at increased risk of disease before they have any symptoms, so that treatment could be commenced earlier.

The Government’s Cancer Expert Working Group on Cancer Prevention and Screening (CEWG) recommends that people at average risk aged between 50 and 75 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 a Colorectal Cancer Screening Programme which subsidise asymptomatic Hong Kong residents aged between 50 and 75 to undergo FOBT screening every two years 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 be referred to an enrolled colonoscopy specialist to receive a colonoscopy examination subsidised by the Government. 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.