Dr Ng Kheng Hong
Colorectal cancer, the most common cancer in Singapore, is also one of the most preventable. Yet, not enough people are going for screening to detect it early at the precancerous stage.
The exact cause of colorectal cancer is unknown, but there are many factors that increase the risk of colorectal cancer, such as age, smoking, lack of exercise, stress, family history, and diseases like diabetes and ulcerative colitis or Crohn's disease.
Colorectal cancer begins with small and benign growths known as polyps. A polyp grows slowly from a few millimetres to about 2cm in diameter before transforming into colorectal cancer. The only proven way to prevent colorectal cancer is to detect these polyps early and remove them before it is too late.
Colonoscopy is a simple procedure that allows doctors to visually examine the bowel lining, to detect precancerous polyps and remove them. Doctors recommend screening colonoscopy for people above the age of 50. Early colorectal cancer may not present with symptoms, and is thus difficult to detect without regular screening.
That is why anyone with colorectal cancer symptoms like rectal bleeding and change in bowel habits should seek medical advice, regardless of age. Those with a family history of colorectal cancer should start colonoscopy earlier and do it more frequently. If the screening result is normal, you should have one every 5 – 10 years afterward. But, if you have had precancerous polyps in your colon, you need regular colonoscopies and the frequency of which is determined by the number and size of the polyps. Your doctor should be able to advise you on this.
Colorectal cancer is preventable since it starts as polyps and take years to become cancerous, if at all. If it is found early, the 5-year survival rate is 90%. Colonoscopy is a safe procedure with a low incidence of complications and is recommended to be done once every 10 years, starting from the age of 50. With recent advancements in colonoscopy, even polyps that are larger than 2cm in diameter can be removed safely via colonoscopy.
Many lives can be saved by understanding colorectal cancer risks, increasing screening rates, and making lifestyle changes. Consult your doctor to assess your suitability for a colonoscopy screening if you experience symptoms like persistent abdominal pain, rectal bleeding, increasing constipation, unexplained weight loss, and a sudden change in bowel habit.
The only proven way of preventing colorectal cancer is early detection and removal of colon polyps before it become cancerous.