Colorectal cancer, commonly known as colon cancer or bowel cancer, originates from the tissues of the colon (the longest part of the large intestine) or rectum (the last several inches of the large intestine before the anus). Most colorectal cancers are adenocarcinomas (cancers that begin in cells that make and release mucus and other fluids).
It is the most common cancer in Singapore. The incidence of this cancer has been steadily increasing in both males and females. Singapore has one of the highest incidence of this cancer in Asia together with Taiwan, Japan and Australia. The good news is that the number of deaths from colorectal cancer has been dropping for the last 15 years. This is because more people are going for regular screening, which can detect colorectal cancers early. Treatment for colorectal cancer has also improved, allowing for patients to be treated more effectively. Early detection of colorectal cancer can normally lead to a complete cure.
There is no single cause of colorectal cancer, as in most cases, colon cancers begin as a polyp that develops into a cancerous growth.
What Causes Colorectal Cancer?
No one knows the exact causes of colorectal cancer. However, we do know that people with certain are more likely than others to develop colorectal cancer. Studies have found the following risk factors for colorectal cancer:
Polyps are growths on the inner wall of the colon or rectum and is common in people over age 50. Most polyps are benign (not cancer), but some polyps (adenomas) can become cancer.
A person who has had a condition that causes inflammation of the colon (such as ulcerative colitis or Crohn’s disease) for many years is at an increased risk.
A person who has already had colorectal cancer may develop colorectal cancer a second time. Also, women with a history of cancer of the ovary, uterus (endometrium), or breast are at a somewhat higher risk of developing colorectal cancer.
If you have a positive family history of colorectal cancer, you are more likely than others to develop this disease, especially if your relative had the cancer at a young age.
Individuals who smoke, or consume a diet that is high in fat and low in fruits and vegetables are at an increased risk of colorectal cancer.
Colorectal cancer is more likely to occur as people get older. More than 90 percent of people with this disease are diagnosed after age 50 years and above.
SIGNS AND SYMPTOMS
Warning Signs of Colorectal Cancer
A common symptom of colorectal cancer is a change in bowel habits. Symptoms include:
- Change in bowel habits (diarrhea or constipation)
- Feeling that your bowel does not empty completely
- Finding blood (either bright red or very dark) in your stool
- Finding your stools are narrower than usual
- Frequently having gas pains or cramps, or feeling full or bloated
- Losing weight with no known reason
- Feeling very tired all the time
- Having nausea or vomiting
Most often, these symptoms are not due to cancer. Other health problems can cause some of these symptoms. Additionally, it is important to note that early cancer does not usually cause pain. Therefore, anyone with these symptoms should see a doctor to be diagnosed and treated as early as possible.
TREATMENT & CARE
Surgery involves the removal of tissues that contain the tumor and nearby tissues/lymph nodes. This may be done via laparoscopy or open surgery.
Chemotherapy uses anticancer drugs to shrink/kill cancer cells. The drugs enter the bloodstream and can affect cancer cells all over the body.
Some people with colorectal cancer that has spread receive targeted therapy. Targeted therapies are drugs or other substances that block the growth and spread of cancer by interfering with specific molecules involved in tumor growth and spread.
Radiation therapy (also called radiotherapy) uses high-energy rays to kill cancer cells. It affects cancer cells only in the treated area.