Colorectal cancer is the most common in Singapore. Approximately 1,800 new cases of colorectal cancer are diagnosed each year or approximately 5 Singaporeans are diagnosed daily, making it the most common cancer in Singapore.
The incidences of colon and rectal cancer in Singapore are amongst the highest in the world and Singaporeans have the dubious honour of having the highest age-standardised incidence of rectal cancer in the world!
A recent report by the Singapore Cancer Registry found colorectal cancer to be one of the 3 leading cancers diagnosed in Singapore, regardless of gender and ethnicity. In fact, colorectal cancer is responsible for approximately 1 in 6 of all cancers in men and 1 in 7 in women, with Chinese having the highest risk.
While surgery is the mainstay of treatment for colorectal cancer, early detection improves the likelihood of a cure and offers a clear survival benefit because it has a long pre-cancerous stage (polyp stage) and when detected at this stage, endoscopic treatment is possible with almost 100% cure.
But all said, it’s more important than anything else to know the facts about colorectal cancer. What is it? Why is it so common in Singapore? And what can you do to minimise your risks?
Colorectal cancer is a cancer of the colon (large intestine) or rectum (the lower part of your large intestine).
Common symptoms are
However, in the early stages (polyp stage or stage-A cancers) colorectal cancers can be completely asymptomatic. In addition, both doctors and patients may be lulled into complacency as some of these symptoms may be caused by benign conditions such as haemorrhoids, irritable bowel syndrome or colitis. So don’t put off visiting your doctor if you are troubled by these symptoms or have a family history of polyps or cancers – it’s important to have a colonoscopy to exclude polyps or cancer.
The majority of colorectal cancers arise from adenomatous polyps. Malignant transformation of adenomatous polyps (adenoma-carcinoma sequence) takes 5 to 10 years via multiple gene mutations. Adenomatous polyps are relatively asymptomatic. They are present in up to 25% of individuals at age 50 and the prevalence increases with age. Most polyps (90%) can be removed at colonoscopy, thereby precluding the need for surgery.
Thus, colorectal cancer has a detectable premalignant phase (adenoma) and a relatively long duration before malignant transformation. Mortality from colorectal cancer can be reduced by screening asymptomatic individuals for the presence of adenomas and early cancers.
Adenomatous polyps are largely asymptomatic.
The process of malignant transformation takes a relatively long time.
Why Is Colorectal Cancer So Common?
There are several reasons why colorectal cancer is becoming more common, not just in Singapore but also around the world. People whom are overweight, smoke, drink alcohol regularly, consume a high-fat diet, or don’t exercise are all at a higher risk of developing it. Type-2 diabetes and low fibre diets are also possible risk factors.
The good news is that modifying your lifestyle to help minimise your risk of developing colorectal cancer also helps prevent the onset of other life-threatening medical conditions such as diabetes, high blood pressure, stroke and heart disease.
Screening should begin at age 50 years for individuals without any risk factors. In certain individuals, screening should begin earlier. Those who have a family member with a history of colorectal cancer or polyps or certain familial cancer syndromes such as familial adenomatous polyposis should have screening at a much younger age.
For a screening test to be widely applicable, it must be inexpensive, reliable and acceptable. It must also be able to detect the cancer at a very early stage or even pre-cancer stage. Various screening tests for colorectal cancer have been studied but Faecal occult blood testing (FOBT) is the only screening modality that has been shown to decrease colorectal cancer mortality by 33%. It is also inexpensive and non-invasive and in light of this, it should be offered to the general population age 50 and above, every year.
The other widespread screening test is colonoscopy and is an adjunct to FOBT. It should be performed at 50 and then every 5-10 years thereafter and whenever an FOBT is positive or other suspicious symptoms arise.
Other screening alternatives may not be as reliable (barium enema and sigmoidoscopy) or be too complex or require very specialised skills (virtual colonoscopy).
Colorectal cancer screening reduces cancer-related deaths (by detecting and removing polyps and cancers before they have spread)
For the general population, screening should start at age of 50 years old and consists of:
FOBT every year and
Colonoscopy every 5-10 years
For individuals with risk of an earlier onset, screening should begin 5 years younger than the age at which their family member developed polyps or cancer or according to your doctor’s recommendations for specific familial cancers
© Abdo-Endoscopy SG 2019 | All Rights Reserved
Disclaimer: The information provided in this site does not replace information from your healthcare professional. Please consult your healthcare professional for more information.