Dr Patricia Kho, a Medical Oncologist at Parkway Cancer Centre, shares some useful information about colorectal cancer, possible preventive measures and medical advancements.
1. It’s common yet treatable
Colorectal cancer is cancer that starts in the large intestine (colon) or the rectum (end of the colon).
It is the most common cancer in developed countries today. People living in these countries carry three times the risk of developing the cancer.
In Singapore alone, 9,324 diagnosed colorectal cancer cases were reported between 2010 to 2014 with both men and women equally at risk. It is now the most common cancer among men and the second most common cancer among women in Singapore. Although it can occur at any age, it is diagnosed mostly in those over 50 years old. If detected early, it can be prevented or effectively treated.
Ninety per cent of colorectal cancer cases almost always start with a polyp. However, it can take five to 10 years for normal cells in the lining of the colon or rectum to mutate and undergo “methylation abnormalities”, where the cells change and grow without control. Through gene mutations over time, a non-malignant polyp can turn cancerous.
2. Beware of inherited risk
It is estimated that about five to 10 per cent of all colorectal cancers may be hereditary.
The two most common inherited colorectal cancer syndromes are hereditary non-polyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP). HNPCC cases account for three to five per cent of the population. FAP cases happen to less than one per cent of the population.
People who carry the same syndrome as their family members carry a higher risk. For example, people with FAP can see more than hundreds of polyps in early teenage life while those with HNPCC often have at least three family members and two generations with colorectal cancer. In this case, the cancer may develop before age 50.
Inflammatory bowel disease (Crohn’s disease, ulcerative colitis) also increases one’s risk of colorectal cancer. The risk is higher if inflammation affects the entire colon.
3. Look on the bright side
From 2005 to 2014, the survival rate has increased from 45 per cent to 50 per cent across all ethnic groups and in both males and females.
Medical advancements particularly in the field of personalised medicine have increased the chances of survival. Genomic profiling has been useful in tailoring treatment according to the cancer characteristics and genetic make-up of the individual.
New drugs such as Cetuximab and Panitumumab, which cleverly block colorectal cancer cells from further growth, are found to work well for advanced-stage patients who carry the non-mutated (wild-type) KRAS and N-RAS gene.
The latest and most promising form of cancer treatment, immunotherapy which marshals the body’s own immune defences against cancer, also offer hope to a particular group of colon cancer patients.
4. Cultivate the good
Stop smoking: Each puff of each cigarette contains more than 60 well-established cancer-causing carcinogens.
Limit alcohol intake: Alcohol can act as an irritant. Damaged cells may try to repair themselves, which could lead to DNA changes in the cells. In the colon and rectum, bacteria can convert alcohol into large amounts of acetaldehyde, a chemical that has been shown to cause cancer in lab animals. Men should limit their intake to two alcoholic drinks and women to one alcoholic drink a day.
Exercise regularly: One hypothesis is that high levels of insulin or insulin-related growth factors in obese people may promote colon cancer development. Maintain a lower end of body mass index (BMI) to reduce the risk of getting colorectal cancer.
Watch the diet: Food consisting of red and processed meats with presence of animal fats like those found in ham, bacon, sausages and local delicacy bak kwa are some examples of foods to avoid excessive intake. An intake of 500 grams of cooked meat per week with large portions of fresh greens and fruits per meal is recommended.
5. Go for a colonoscopy
Many are still unaware of the role of a colonoscopy in preventing colorectal cancer.
Because it takes five to 10 years for a polyp to become cancerous, screening colonoscopy – a painless and fuss-free procedure – can make a big difference. This should be done for people aged 45 to 50, once every five years.
High-risk individuals with family members who have had colorectal cancer should go for a colonoscopy earlier after discussion with the relevant medical professionals.
Find out more about cancer and how to fight it on ST's Fighting Cancer microsite.