Colorectal Cancer

Colorectal Cancer is the cancer of the colon (large intestine) and the rectum (the passageway connecting the colon to the anus). Colorectal Cancer is Singapore's top killer, affecting more than 1,865 cases each year. Colorectal Cancer usually starts as a non-cancerous polyp (a growth of tissue) on the inner lining of the colon or rectum which may develop into cancer over time. This is why screening using colonoscopy is important as the polyp can be detected and removed before it becomes cancerous. Rectal cancers account for around 30% of the total number of colorectal cancers seen here. Screening for Colorectal Cancer saves lives.

Colorectal Cancer is often a silent disease, developing with no symptoms at all. When symptoms do occur they may include the following:

• Rectal bleeding or blood (either bright red or very dark) in the stool
• A change in bowel habit
• Persistent abdominal discomfort such as cramps or pain
• Incomplete emptying of the bowel
• Unexplained weight loss
• Unexplained anaemia

Consult your doctor if you experience these symptoms.

Regular screening can often detect Colorectal Cancer early, when it is most likely to be curable. In many cases, screening can also prevent Colorectal Cancer as some polyps or growths can be removed before they have the chance to develop into cancer.

Screening for Colorectal Cancer:

• Prevents cancer by removing polyps during colonoscopy
• Detects early cancers with a good chance of a cure

There are several tests that examine the colon and rectum and are used to find and diagnose Colorectal Cancer.

Your doctor checks general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual.

The doctor inserts a lubricated gloved finger into the rectum to feel for lumps or anything that seems unusual. However, this detects cancer only in the last 5 to 8 centimetres of the rectum.

An X-ray test using barium sulphate (a chalky liquid) to outline the inner part of the colon and rectum to look for abnormal areas on x-rays. If suspicious areas are seen, a sigmoidoscopy or colonoscopy will be needed to explore further.

This procedure examines the rectum and the sigmoid (lower) colon for polyps, abnormal areas or cancer. A flexible, thin, tube-like instrument with a light and a lens for viewing is inserted through the rectum into the sigmoid colon.

This procedure allows examination of the whole colon for cancer. A colonoscope (a thin, tube-like instrument) is inserted through the rectum into the colon.

The following are at risk of Colorectal Cancer:

• Men and women 50 years and above
• Individuals with a personal or family history of colon or rectum cancer
• Individuals with a Personal or family history of colon polyps
• A history of inflammatory bowel disease such as ulcerative colitis (ulcers in the lining of the large intestine) or Crohn’s disease

Colorectal Cancer can affect both sexes of any age and any race. It is more common after the age of 50 years, and more common among the Chinese. For Colon Cancer, the incidence is the same between males and females, whereas Rectal Cancer is more common among males.

Screening should begin at age 50 years for individuals without any risk factors. In individuals with an increased risk, screening should begin earlier, before the age of 50, depending on the risk factor(s) present.

People who think they are at risk should discuss this with their doctor.

• Practice a healthy lifestyle and maintain a healthy weight (low-fat diet, high in fibres, regular exercise and avoid alcohol intake)
• Screening is advised for men and women 50 years and above with colonoscopy or Faecal Immunochemical Test (FIT)

The FIT test checks for hidden blood in the stool, which can be an early sign of Colorectal Cancer. The test comes in a simple kit and can easily be carried out in the comfort of your own home. Another advantage is that dietary restriction is not required in immunochemical testing. The FIT test needs to be done annually to be an effective screening test.

A colonoscopy is a procedure that enables your doctor to examine the lining of your colon for abnormal growths. A soft and flexible tube, about the thickness of a finger, is gently inserted into the anus and advanced in. The tube has a built-in camera that allows your doctor to see your colon. The procedure usually takes about 15 to 30 minutes to complete.

The main advantages are its high sensitivity and specificity and the long recommended screening interval of 10 years. The protective effect of colonoscopy is attributed to the ability to remove asymptomatic polyps before malignant transformation occurs.

Usually, bowel preparation takes 1 of 2 forms: high-volume (3-4 litres) polyethene glycol (PEG) or low-volume (90 ml) oral fleet. Oral fleet is contraindicated in patients with renal impairment due to its high phosphate content. For suitable patients, it is a more palatable option as it can be mixed with sweetened fluids. Patients taking oral fleet must be encouraged to drink plenty of water to decrease the likelihood of phosphate toxicity.

Oral medications which need to be stopped before colonoscopy:

• Iron supplements (1 week before appointment)
• Anticoagulation medications e.g. aspirin, ticlid, warfarin (5 days before the appointment)

Patients should go on a low fibre diet 3 days before colonoscopy, and avoid:

• Fruits and vegetables including fresh fruit and vegetable juices
• Vegetable soup
• Red meat
• Milk products
• Cereals and grains e.g. oats, bran, wheat, muesli, barley, nuts and beans

Foods allowed include:

• Simple carbohydrates (white rice, white bread, mee sua, bee hoon, kway teow, potatoes)
• Fish
• Plain coffee, tea, glucose, honey or clear soup

Colonoscopy is the gold standard for large bowel evaluation. The screening interval for colonoscopy is 10 years. Bowel preparation with low-volume oral fleet is feasible in the absence of contraindications.

Depending on the stage of the colorectal cancer, there are various treatment options available. The main types of treatment that can be used for colorectal cancer include the following.

Surgery is the most common kind of treatment for all stages of Colorectal Cancer. There are various forms of surgery to remove the cancer including:

• Local excision: If the cancer is found at a very early stage, the doctor may remove it with colonoscopy (without the need to cut through the abdominal wall). A tube will be put through the rectum into the colon to remove the cancer.
• Resection: If the cancer is larger, the doctor will remove the part of the colon containing the cancer and lymph node, along with a small amount of healthy colon on either side of the cancer. This is called colectomy. The ends of the colon are then reconnected. This is called anastomosis. If the doctor is not able to reconnect the two ends of the colon, a stoma is made on the outside of the body for waste to pass through. A bag is placed around the stoma to collect the waste. Today, many surgeries can be performed using minimally invasive surgical techniques (key-hole surgery). Minimally invasive surgery has been shown to result in faster recovery with less postoperative pain.

Radiation therapy uses high-energy X-rays or other types of radiation to kill cancer cells or keep them from growing. Radiation therapy is usually used after surgical removal of the cancer to kill any residual cancer cells around the original tumour site. It can also be used together with chemotherapy to shrink a large colorectal cancer before surgery.

Chemotherapy is the use of drugs to stop the growth of cancer. It can be administered by injecting drugs into the vein or taken by mouth as pills. Depending on the stage of the cancer, chemotherapy may be required after surgery to prevent recurrence and improve a person's chance of survival. Chemotherapy is commonly used for patients with advanced Colorectal Cancer which cannot be cured by surgery or have spread to other parts of the body. The many different treatment options available have enabled advanced Colorectal Cancer patients to live longer despite having an incurable cancer. Treatment for advanced colorectal cancer is now personalised with genetic information from the cancer used to guide the selection of medications such as targeted therapy and immunotherapy. Targeted therapy uses drugs to help stop cancer from growing and spreading. They work by targeting specific genes or proteins found in cancer cells, or in cells related to cancer growth, like blood vessel cells. Immunotherapy is the newest form of cancer treatment. It is a type of cancer treatment designed to allow the immune system itself to destroy the cancer cell.