The large intestine, or colon, is where the body extracts salt and water from the stool before it is moved into the rectum and expelled through the anus. Colon cancer, or colorectal cancer, refers to cancer of the large intestine – the final portion of our digestive tract. Polyps, which are either non-cancerous (benign) or pre-cancerous growths, may form on the inner wall of the colon and rectum. One of the most common cancers in Singapore is colon cancer, which affects both men and women.
What are the causes and risk factors for colon cancer?
The process of cancer begins when healthy cells in the colon undergo changes (mutations) in their DNA. Numerous changes in the DNA over time are required before these cells go rogue and multiply out of control. Most of these DNA changes are sporadic and occur in the later stages of our lives. Certain modifiable risk factors increase the chances of acquiring these DNA changes. They include:
- A diet high in processed meat and low in fiber
- Excess alcohol consumption
- Smoking
- Obesity
- Lack of physical exercise
- Type 2 Diabetes Mellitus
Other risk factors that are beyond our control include:
- Older age
- Male gender
- Personal or family history of colorectal polyps
- Personal or family history of colorectal cancers
- Personal history of inflammatory bowel disease
- Inherited genetic syndromes linked to colorectal cancers, e.g., Lynch syndrome
- Familial adenomatous polyposis (FAP), which accounts for 5% of all colorectal cancers
What are the symptoms of colon cancer?
The symptoms of colorectal cancer depend on the location of the cancer within the large intestine, how advanced it is, and how it affects the adjacent organs. As some symptoms do not appear until the cancer has reached an advanced stage, it is important to have early and regular colorectal screening. Signs and symptoms of colorectal cancer include:
- Change in bowel habits (diarrhea or constipation)
- Feeling that your bowel does not empty completely
- Feeling very tired all the time (symptom of anemia)
- Finding blood (either bright or dark red) in your stools
- Finding your stools are narrower than usual
- Frequently having intestinal cramps, or feeling bloated
- Losing weight for no apparent reason
Sсrееnіng for colorectal cancer
Colon cancer is one of the few cancers that are actually preventable. Prevention of colon cancer is done through regular screening. All persons above the age of 50 should go for colonoscopy screening regardless of the presence of symptoms. Alternatively, colorectal cancer screening may be done using a stool occult blood test. This is a simple, self-administered test that is available from any polyclinic or GP clinic, as well as various organizations such as the Singapore Cancer Society. The stool occult blood test should be repeated yearly.
Most common treatment for early-stage colon cancer
In the earliest stages where cancer is confined within the polyp, surgery may successfully remove the cancer before it has spread, thereby achieving a cure. If the cancer has spread through the bowel wall, it is important to remove the involved portion of the colon or rectum together with the draining lymph nodes. This comprehensive surgery is designed to achieve a cure and reduce the chances of a future cancer recurrence. When feasible, the surgery is performed laparoscopically (keyhole surgery) so that a faster post-operative recovery and healing is achieved.
After the involved colon or rectum is removed, it is important to re-attach the remaining healthy portions of the large intestine so that a normal intestinal function is preserved. This is known as an intestinal anastomosis. If an anastomosis cannot be performed or the risk of performing one is too high, a stoma may be created. This involves the attachment of the colon to a small opening in the abdominal wall for the expulsion of fecal material into a stoma bag. Sometimes the stoma is only intended for a short duration before it is re-attached to achieve a normal intestinal function once again. This is then known as a temporary stoma.
The sooner the treatment, the greater the chances of cure. Improvement in surgical techniques, anesthesia, and post-operative care enables treatment to be offered to patients who were previously deemed too old or too frail.
Chemotherapy may also be recommended after surgery for early-stage colorectal cancer. Such adjuvant treatment is intended to reduce the chances of the cancer recurring.
Taking the time to discuss the various treatment options with our doctor enables you to make an informed decision. This is vital to ensuring overall success in your treatment plan. By understanding the risks and benefits of each treatment option, while anticipating the challenges as they present, you can be assured that we will be journeying with you throughout the cancer treatment to ensure the best outcome.
