Colorectal Cancer

Colon Cancer Specialist Singapore
Colorectal Cancer
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

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.

Treatment of colorectal cancer

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.

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.