Colorectal cancer (CRC) is the top cancer in males and second most common females in Singapore.* Our numbers are approaching that in developed countries such as US and England and are increasing every year. The risk ratio for an average Singaporean to contract this cancer is about 1 in 50.
CRC is more common in people after 50 years old. The peak incidence is people in their seventies. The Chinese has a significantly higher risk than the Malays or Indians.
* Singapore Cancer Registry, Interim Report, 2001-2005
Risk Factors:
1. Males and females > 50 years old
2. Chinese has a higher risk among the races in Singapore
3. Family history
Some individuals inherit a rare disease called familial polyposis in which many colorectal polyps develop at a young age. The risk of developing CRC is very high (80 to 100%). Such individuals should consider having the colon removed before the age of 40 years old.
Another type of inheritance is an individual with a relative with polyps or CRC. He/she is also at a higher risk of CRC (although the risk is low compared to a familial polyposis individual).
4.
Ulcerative Colitis (UC)
This is a disease affecting the bowels leading to inflammation and cancerous change in the long term. People with UC have a significant risk of CRC.
5.
Dietary Habits
Research has identified certain types of food and food supplements which can affect our risk of CRC:
| Food that increase the risk |
Explanation |
| Meat, cooked at high temperature |
It contained chemicals, e.g. heterocyclic amines that are carcinogenic |
| Animal fat |
Fat is converted to bile acids which can promote cancer change in the mucosa of the colon |
| Tobacco and Alcohol |
Tobacco has been shown to increase polyp formation |
| Food that reduce the risk |
Explanation |
| Fibre (vegetables, fruits, bran) |
Fibre help to reduce the transit time of faeces and to dilute the carcinogens in the colon |
| Vitamin Supplement (especially folate) |
Studies have shown that regular multivites & folate can reduce CRC risk |
| Mineral intake esp calcium |
Calcuim can bind to fatty acids and bile acids and reduce our risk. |
6. Drugs
Current users of HRT (hormone replacement therapy) are at a lower risk of CRC and this protection disappears within 5 years of stopping the HRT.
Aspirin and NSAID (a strong painkiller drug) are known to reduce the risk from CRC. However it is too early at this stage of research to recommend the routine use of these drugs for this purpose.
7. Sedentary lifestyle and obesity
These two related factors increase the risk of CRC. Physical Activity helps to regulate the transit time of faeces in the colon and hence can reduce the risk.
8. Past history of colorectal polyp or colorectal cancer
Despite knowing all these risk factors, the exact cause of CRC remains unknown. It is estimated that 50% of CRC patients have no known risk factors.
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