Colorectal cancer is the cancer of the colon (large
intestine) and the rectum (the passageway connecting the colon to the anus).
Colorectal cancer is Singapore's top killer, affecting more than 1,865 cases
each year. Colorectal cancer usually starts as a non-cancerous polyp (a growth
of tissue) on the inner lining of the colon or rectum which may develop into
cancer over time. This is why screening using colonoscopy is important as the
polyp can be detected and removed before it becomes cancerous. Screening for
colorectal cancer saves lives.
- Men and women 50 years and above
- Personal or family history of colon or rectum cancer
- Personal or family history of colon polyps
- A history of inflammatory bowel disease such as ulcerative colitis (ulcers in the lining of the large intestine) or Crohn’s disease
*People who think they may be at risk should discuss this with their doctor.
Colorectal cancer is often a silent disease, developing with no symptoms at all. When symptoms do occur they may include the following:
- Rectal bleeding or blood (either bright red or very dark) in the stool
- A change in bowel habit
- Persistent abdominal discomfort such as cramps or pain
- Incomplete emptying of the bowel
- Unexplained weight loss
*A doctor should be consulted if the symptoms above occur.
Regular screening can often detect colorectal cancer early, when it is most likely to be curable. In many cases, screening can also prevent colorectal cancer as some polyps or growths can be removed before they have the chance to develop into cancer. There are several tests that examine the colon and rectum and are used to find and diagnose colorectal cancer.
Physical Exam
Your doctor checks general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual.
Digital Rectal Exam
The doctor inserts a lubricated gloved finger into the rectum to feel for lumps or anything that seems unusual. However this detects cancer only in the last 5 to 8 centimeters of the rectum.
Barium Enema
An x-ray test using barium sulfate (a chalky liquid) to outline the inner part of the colon and rectum to look for abnormal areas on x-rays. If suspicious areas are seen, a sigmoidoscopy or colonoscopy will be needed to explore further.
Flexible Sigmoidoscopy
This procedure examines the rectum and the sigmoid (lower) colon for polyps, abnormal areas or cancer. A flexible, thin, tube-like instrument with a light and a lens for viewing is inserted through the rectum into the sigmoid colon.
Colonoscopy
This procedure allows examination of the whole colon for cancer. A colonoscope (a thin, tube-like instrument) is inserted through the rectum into the colon.
Depending on the stage of the colorectal cancer, there are various treatment options available. The main types of treatment that can be used for colorectal cancer include the following.
Surgery
Surgery is the most common kind of treatment for all stages of colorectal cancer. There are various forms of surgery to remove the cancer including:
Local excision: If the cancer is found at a
very early stage, the doctor may remove it with colonoscopy (without the need
to cut through the abdominal wall). A tube will be put through the rectum into
the colon to remove the cancer.
Resection: If the cancer is larger,
the doctor will remove the part of the colon containing the cancer and lymph
node, along with a small amount of
healthy colon on either side of the
cancer. This is called colectomy. The ends of the colon are then reconnected.
This is called anastomosis. If the doctor is not able to reconnect the
two ends of the colon a stoma is made on
the outside of the body for waste to pass through. A bag is placed around the
stoma to collect the waste. Today, many surgeries can be performed using
minimally invasive surgical techniques (key-hole surgery). Minimally invasive
surgery has been shown to result in faster recovery with less postoperative
pain.
Radiation Therapy
Radiation therapy uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. Radiation therapy is usually used after surgical removal of the cancer to kill any residual cancer cells around the original tumour site. It can also be used together with chemotherapy to shrink a large colorectal cancer before surgery.
Chemotherapy, Targeted Therapy and Immunotherapy
Chemotherapy is the use of drugs to stop the growth
of cancer. It can be administered by injecting drugs into the vein or taken by
mouth as pills. Depending on the stage of the cancer, chemotherapy may be
required after surgery to prevent recurrence and improve a person’s chance of
survival. Chemotherapy is commonly used for patients with advanced colorectal
cancer which cannot be cured by surgery or have spread to other parts of the
body. The many different treatment
options available have enabled advanced colorectal cancer patients to live longer
despite having an incurable cancer and they are managed with having a chronic
condition. Treatment for advanced colorectal cancer is now personalized whereby
genetic information from the cancer is used to guide the selection of
medications such as targeted therapy and immunotherapy. Targeted therapy uses
drugs to help stop cancer from growing and spreading. They work by targeting
specific genes or proteins found in cancer cells or in cells related to cancer
growth, like blood vessel cells. Immunotherapy is the newest form of cancer
treatment. It is a type of cancer treatment designed to allow the immune system itself to destroy the cancer cell.
