Introduction to Cancers of the Colon & Rectum
Cancers of the colon and rectum are now the top cancers in men and women. From 2009-2013, nearly 9000 cases are diagnosed in Singapore, mostly in the Chinese ethnic group.
Early colorectal cancers (Duke’s Stage A and B) are curable by surgery alone. Late stages (Duke’s C and D) will require chemotherapy for control of disease and improve survival.
Methods of Colorectal Cancer Screening
There are several screening methods to detect early colorectal cancers.
- Fecal Occult Blood Test (FOBT) – This involves sending a stool sample inside a test kit to examine for small quantity of blood. Although the test has become more sophisticated over the years, it remains non-specific.
It is unable to determine whether the source of bleed is benign or cancerous, nor can it locate the point of bleeding. Furthermore, once positive, a more sophisticated test like colonoscopy is mandated.
- Barium Enema – This involves instilling a special dye into the colon, and then taking a series of X rays. It is largely obsolete now.
- Fiberoptic Colonoscopy – This involves passing a special telescope with a HD camera into the bowel by a trained specialist. This procedure is highly accurate, comfortable, and very safe. Even small 2mm polyps can be accurately detected.
The procedure performed under light sedation and over in 15-20 minutes. Patients are discharged home after a brief period of observation. This is currently the gold standard in accurately detect early colorectal cancer.
- CT Colonograph – Also known as “virtual colonoscopy”, this involves using CT scan to collect a series of images and then reconstructing them into a 3 dimensional colonic image using computer software.
It involves a large amount of radiation, can be inaccurate and can miss small lesions. Also if a polyp was found, a fiberoptic colonoscope needs to be ordered again. This is currently an alternative for patients who for any reason cannot undergo a fiberoptic colonoscopy.
Ministry of Health of Singapore recommends an initial screen at the age of 50 for asymptomatic, low risk individuals. If the test is negative, then 10 yearly screening will be enough.
High risk individuals include the following
- Family History of Colorectal Cancer and Polyps – screening should start 10 years earlier than the age of the affected individual. For example, if a person developed colorectal cancer at the age of 55, the close relatives should go for screening at age 45 instead of waiting till 50 years old
- Personal History of Polyps – repeat screening should be done within 3-5 years
- Personal History of Colorectal Cancer – Screening should take place 1 year after surgery, and 3 yearly thereafter.
Conclusion: Colorectal Cancer Screening is Important
Colorectal cancer is common. Early screening is the only way to detect the disease at its early stage. This then results in safe and efficient surgery, and cure without the need for chemotherapy.
Colonoscopy is currently the most accurate method to screen for early cancer. It’s comfortable, safe and has minimal downtime.