Colorectal Cancer

Colon Cancer Specialist Singapore
Colorectal Cancer in Singapore
By Dr. Tan Wah Siew
Colorectal cancer (colon cancer and rectal cancer combined) is the most common cancer in Singapore, affecting both males and females, although males have a slightly higher risk of contracting the disease.

Who are at risk of colorectal cancer?

The single most important risk factor in the development of colorectal cancer is age, with the risk increasing substantially after the age of 50. Although young patients can also develop colorectal cancer, approximately 75-80% of patients diagnosed are over the age of 55.

Individuals with a family history of colorectal cancer are also at increased risk, particularly if there are multiple family members affected, the family members are first degree relatives, or if one or more were less than 50 years old at diagnosis.

It is important to note, however, that more than 80% of patients have sporadic colorectal cancer, which means that most patients with colorectal cancer do not have a family history.

Individuals with genetic conditions like hereditary non-polyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP) have a markedly increased risk of developing colorectal cancer at a young age. These syndromes are relatively rare, accounting for only approximately 5% of patients diagnosed with colorectal cancer (see section on HNPCC and FAP).
Individuals with IBD have a higher risk of developing colorectal cancer, and require close colonoscopy surveillance to detect colorectal cancer or precancerous lesions. (See section on Inflammatory Bowel Disease)
  • A diet high in red and processed meat, and low in fibre
  • Smoking
  • Alcohol intake
  • Obesity and lack of physical activity

What are the Symptoms of Colorectal Cancer?

Early stage colorectal cancer usually does not manifest any symptoms. Hence by the time there are symptoms, it is likely that intermediate or late stage cancer may be diagnosed.

Some symptoms of colorectal cancer include:

  • Blood in the stools
  • Change in bowel habits
  • Diarrhoea
  • Constipation
  • Mucus in the stools
  • Unexplained weight loss and/or poor appetite
  • Abdominal pain/distension

Regardless of age, having these symptoms does not mean that you definitely have colorectal cancer. Rather, it means that you should consult a colorectal surgeon, so that tests can be performed to assess if you have cancer.

Can colorectal cancer be prevented?

Yes! Colorectal cancer almost always develops from precancerous polyps. Hence regular screening with colonoscopy is the key to preventing colorectal cancer.

In Singapore, the Ministry of Health recommends screening for an average risk individual to begin at age 50. Individuals with a family history of colorectal cancer may need to start screening at an earlier age. For example, to start screening at age 40 or 10 years prior to the youngest case in the family (whichever is younger) if there is one 1st degree relative with colorectal cancer below the age of 60.

The American Cancer Society, in 2018, suggested to consider lowering the screening age to 45 years old. There is clear evidence of the benefit of this recommendation but this has not been adopted in Singapore likely because of the lack of cost effectiveness.

Faecal occult blood test (FOBT)
Yearly FOBT is a common population screening method. This detects the presence of blood in the stool. FOBT enables detection of cancers but is not meant to detect polyps as polyps, unless very large, do not usually bleed. Those with a positive FOBT will have to undergo a colonoscopy to rule out colorectal cancer.

Colonoscopy, which examines the inner lining of the colon and rectum, is a more robust screening method as it allows detection and removal of polyps before they turn into cancer. Removal of these polyps during colonoscopy is a proven effective way of preventing the progression to cancer. If a cancer has already developed, it is also more likely to be discovered at an earlier stage on a screening colonoscopy, when treatment has a higher chance of cure.

Other options for colorectal cancer screening
  • CT Colonography
  • Double Contrast Barium enema

However the evidence for the use of these 2 options for colorectal cancer screening is less strong, and a colonoscopy is still required to confirm any diagnosis if an abnormality is found on barium enema or CT colonography.

How is Colorectal Cancer Treated?

Colorectal cancer is a highly curable form of cancer, especially if detected in the early stages.

Colorectal Cancer Surgery

The mainstay of treatment is colorectal cancer surgery, by removing the segment of affected bowel. While this appears daunting, most patients are able to have their bowel continuity restored during the surgery, allowing them to continue to move their bowels through the anus, as they did prior to surgery. A small number of patients may require a stoma, but usually only temporarily.

In addition, most patients can have their surgery performed with minimally invasive techniques, either laparoscopically or robotically using the da Vinci robot.

Types of colorectal cancer surgery include:

  • Open Surgery – This is the traditional type of surgery in which the colorectal cancer surgeon makes a large incision in the abdomen and removes the tumour as well as other diseased parts of the colon and/or rectum.
  • Laparoscopic Surgery – This is a minimally invasive procedure whereby only a few small incisions are made, and a thin tube with a camera and light (laparoscope) is inserted, together with long thin instruments, to allow the colon cancer surgeon to clearly visualise and treat the affected area.
  • Robotic Surgery – In this technique, specialised surgical instruments, inserted through small incisions, are attached to advanced robotic arms that the surgeon guides to remove the tumour with high levels of precision.
  • Transanal endoscopic removal of rectal tumours – Benign rectal polyps or selected early stage rectal cancers can be removed via the anus, without the need for removal of a whole segment of bowel.

Advantages of Miminally Invasive Colorectal Cancer Surgery:

  • Faster recovery
  • Shorter hospital stay
  • Less pain
  • Smaller wounds with better cosmesis
  • Lower risk of long term complications like adhesions and incisional hernia.

Radiotherapy and/or chemotherapy

Patients with more advanced disease may require treatment with radiotherapy and/or chemotherapy in addition to surgery.

With better understanding of the disease, improved surgical techniques and better chemotherapy drugs, selected cases of Stage IV cancer or locally advanced cancers where the tumour has involved surrounding organs may also potentially be cured.

How Does One Prepare for Colorectal Cancer Surgery?

Before undergoing colorectal cancer surgery, you may need certain preparations, which may include:

  • Stopping certain medications – Your doctor will advise you on which medications (if any) may need to be temporarily stopped before surgery.
  • Eating and drinking – You may be given specific instructions on bowel preparation prior to the surgery; and be expected to fast for around 8 hours prior to your surgery.
  • Preoperative testing – Your doctor may perform certain tests, such as chest X-rays, ECG or blood work, to confirm that you are fit for the surgery.

What Can I Expect after Colorectal Cancer Surgery?

After the surgery, you will be taken to a recovery room to rest, while your vital signs are being monitored. You may experience some pain and discomfort, but medications will be given to alleviate the pain. Additionally, your doctor may prescribe antibiotics to prevent infection.

If bowel resection is performed, be prepared to stay in hospital for about 4 to 7 days. Once your doctor has determined it is safe for you to go home, you will be discharged with instructions on how to care for yourself. It’s important to follow these instructions carefully to ensure a smooth recovery.

Post-Operative Care?

After colorectal cancer surgery, properly caring for your wound and making necessary dietary and lifestyle changes are important. This includes drinking plenty of fluids, eating a healthy diet and exercising regularly (as advised by your physiotherapist). You should also watch for signs of infection or other complications, such as excessive abdominal pain, bleeding, or fever. If you experience any of these symptoms, contact your doctor or head to the emergency department immediately.


Colon cancer is often very treatable and, in the early stages, curable. The earlier colorectal cancer is detected, the higher the chances of cure.

In Singapore, colorectal cancer is the most common cancer in men and the second most common cancer in women. More than 2000 people are diagnosed yearly with colorectal cancer in Singapore.

Eating a diet high in fiber, such as fresh fruits and vegetables, whole grains, beans and legumes, can help reduce your risk for colorectal cancer. Additionally, avoiding processed foods and limiting red meat intake can also help lower your risk. A higher Vitamin D intake has also been found to reduce the risk of colorectal cancer.

Both haemorrhoids and colon cancer can lead to blood in the stools, and it may be difficult to differentiate one from the other without seeing a doctor and/or going for appropriate tests.

The average life-time risk of contracting colorectal cancer is about 5% in Singapore. This risk increases by 3 to 5 times if you have a first-degree relative (e.g. a parent) who has had colorectal cancer. The risk is also further increased if the relative developed colorectal cancer at a young age (< 50 years old).

Colorectal cancer usually takes several years to develop from a benign polyp to cancer – all while potentially not displaying any symptoms through the early stages of cancer. The risk of developing cancer and polyps increases with age. This makes timely colonoscopies all the more important,as precancerous polyps can be removed before they have a chance of progressing to cancer.