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Symptoms And Risks

Who are at Risk?


Less than 5% of the cancers are considered genetic cancers. These are conditions due to abnormalities in the genetic constitution of the patient.


In Singapore, the lifetime risk of colorectal cancer is about 2%. Most colon and rectal cancer occurs in patients over the age of 50 years, though this does not mean that people below that age will never get colorectal cancer.

Family History

The risks increases when one has close family members with colorectal cancer.


When there is a first degree relative (parents, siblings or children) with colorectal cancer, the risks increase 3 times to about 6%. If this relative is below the age of 50 at the time of diagnosis, the risk goes up to about 10%. If there are 2 first degree relative (for example, father and brother) with colorectal cancer, the risk is 17%. With 3 first degree relative, the risk is almost 50%.

Personal History of Colonic Polyps and Colon Cancer

If you have a history of polyps (adenoma type) or colorectal cancer, there is an increased risk of getting a cancer / 2nd cancer. The greater the number of polyps and the earlier the age of the first cancer, the higher the risk

Personal History of Inflammatory Bowel Disease

Inflammatory bowel disease is a type of chronic inflammation of the intestines. This is more common in the Caucasian population than in Asia. The risk of colorectal cancer is increased with people with this condition and they require long term specialist care for treatment, surveillance and cancer prevention. In certain cases, they are recommended to have colorectal surgery to remove the entire colon and rectum to avoid developing cancer.

If you are at an increased risk of colorectal cancer, seek medical attention to determine a recommended screening schedule and personalised risk management advice.

What are the Signs and Symptoms?

It is important to note that polyps, even large ones, and early cancer may not have any symptoms at all. Symptoms also depend on the site of the cancer and how far away it is from the end of the colon. When stools enter the colon from the small intestines, it is in a semi-solid state. As it stays and travels along the colon, the water in it gets absorbed by the colon and it becomes more solid.

As such, tumour in the right side of the colon do not usually cause much symptoms as the semi-solid stools can flow past most tumours quite easily. The cancer may bleed silently as it is mixed in the stools and cannot be seen with the naked eye. Patients with tumours here usually present late with symptoms of anemia (low blood levels). Symptoms of anemia include tiredness, feeling breathless when walking the same distance or climbing stairs, frequent giddiness.

At the left side of the colon, the stools are more solid. Therefore, any narrowing of the colon lumen results in the following disturbance of the bowel habit:
  • The stools might seem to be narrower in size.
  • Patients might also feel constipated as it is more difficult for the stools to squeeze through a narrower passageway. This might also alternate with diarrhea or loose stools as this type of stools can pass through the narrowed passageway more easily.
  • Patients might also notice blood coating the stools. As a general guide, the blood seen is usually dark red in colour.
It’s important to note that the early stages of colorectal cancer, as well as pre-cancerous polyps, often do not have any symptoms.
Should you experience any of these symptoms, please do not delay seeking medical attention.
For tumours in the rectum, the patient may have the sensation of incomplete passage of stools. This is because the presence of the tumour there imitates the presence of stools.

Other less specific symptoms include feeling of bloating and mucus in the stools. Pain is usually not a feature of colon and rectum cancer until it is at an advanced stage. One complication of the tumour is intestinal obstruction. This means that the entire passageway is blocked and the stools (and even flatus) are not able to pass through. This results in abdominal pain, distension and at a later stage, vomiting. Intestinal obstruction is an emergency medical condition.

Physical examination usually does not yield much signs unless the cancer is in an advanced stage. A hard mass in the abdomen is usually a sign of a large tumour. An enlarged liver signifies spread of the cancer to the liver. In some rectal cancers, a digital rectal examination where your colorectal doctor inserts a finger up the anus may pick up earlier cancers. As such, if your colorectal doctor thinks that you warrant a rectal examination, please do not decline or refuse for fear of discomfort or embarrassment.
Read on for More Information on Colorectal Cancer:
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Our Colorectal Cancer Surgeon
Ho Kok Sun Colorectal clinic logo
Dr Ho Kok Sun
Colorectal & General Surgeon
MBBS (Singapore),
M Med (Gen Surg) (Singapore),
FRCSEd (Gen Surg), FAMS
Dr Ho Kok Sun has been committed to treating colorectal cancer in Singapore for over a decade. He was the past President of the ASEAN Society of Colorectal Surgeons and the Society of Colorectal Surgeons (Singapore), as well as a founding member of the Eurasian Colorectal Technologies Association. Dr Ho was actively involved in the training of medical students and residents, and has published widely in reputable journals and book chapters. He believes that treatment should always be personalised to the patient’s needs.

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Ho Kok Sun Colorectal clinic logo
Ho Kok Sun Colorectal

Colorectal Surgeon

3 Mount Elizabeth,
Mount Elizabeth Medical Centre
#12-09, Singapore 228510

Tel (+65) 6737 2778
Fax : (+65) 6737 2389

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