Colorectal cancer is cancer of the colon and rectum. The colon and rectum are segments of the large intestine that play an important role in the body's ability to digest food and pass waste.
Colorectal cancer is one of the commonest malignancies in the world. In 2002, it was the top and third most frequently reported cancer in males and females respectively in West Malaysia. Chinese had the highest reported incidence of colorectal cancer.
At present, the cause of colorectal cancer is not completely understood. However, it is thought to involve many factors developing over a long period of time.
Age: The incidence of the disease increases exponentially with age. More than 90 per cent of the colorectal cancer cases in Malaysia occur in people over the age of 40.
Polyps: Most colorectal cancer begins in polyps. This non-cancerous growth occurs in the lining of the large intestine. Certain types of polyps can develop into cancer.
Family history : People whose family members have colorectal cancer, especially at a young age, have a higher risk of developing this disease.
Personal history of cancer: Women who have had cancer of the ovary, uterus or breast are more likely to develop colorectal cancer.
Diet : A diet high in fat and low in fibre is linked to the development of the disease.
Tobacco : smoking increases the risk of polyp formation
Body weight and physical activity: People with sedentary lifestyles and who are overweight or obese increase their risk of colorectal cancer.
Nonsteroidal anti-inflammatory drugs (NSAIDS): Some studies suggest that taking aspirin and other NSAIDS may reduce the risk of developing polyps.
Inflammatory Bowel Disease: This rare disease in Malaysia is a known risk factor in the West.
Symptoms And Diagnosis
People with colorectal cancer may develop a number of non-specific symptoms. These include a change in bowel habits; diarrhoea; constipation or a feeling that the bowel does not empty completely, and stools with bright red or very dark blood.
They may also experience abdominal pain, including frequent bloating, fullness and cramps. Stools may appear thinner. They may also be constantly tired and anaemic, or experience an unexplained loss of weight and appetite.
The doctor may perform some tests to make a diagnosis. Sigmoidoscopy or colonscopy may be performed. These procedures allow the doctor to look inside the large intestine. During this procedure, the doctor can remove polyps or other tissue for examination.
Blood tests and other imaging tests may also be useful.
Stage I : Cancer is confined to the inner lining of the colon or rectum.
Stage II : Cancer spreads through the wall of the colon or rectum.
Stage III : Cancer spreads to nearby lymph nodes.
Stage IV : Cancer spreads to distant parts of the body, such as the liver or lungs.
Like most cancers, the treatment of colorectal depends on the specific location and extent of the disease.
Surgery is the most common treatment for colorectal cancer, and aims to remove the tumour and part of the healthy intestine and the nearby lymph nodes.
Some patients may require a colostomy, which is a surgical opening through the abdomen to provide a pathway for the waste to exit the body into a bag worn by the patient. This opening is usually temporarily but may be permanent in some cases.
In colorectal cancer, chemotherapy is often used to kill cancer that may have spread to the other parts of the body from the original tumour. It has been shown to reduce the risk of the cancer returning in the future.
Chemotherapy also can help people with advanced stage cancer to live longer and more comfortably. This treatment may cause some side effects, but they are usually short lived and manageable.
Radiotherapy, which uses high energy radiation to kill cancer cells, is commonly used in rectal cancer. It is painless and does not involve electrical currents on patients, as is often thought.
Screening means detection of cancer before there are any symptoms.
As most colorectal cancers develop from benign polyps over a period of several years, it provides a window of opportunity for the detection and removal of pre-cancerous polyps and early stage cancer.
For screening in Malaysia, healthy people aged between 40 and 45 years may undergo an annual faecal occult blood test (which detects blood in the stool), flexible sigmoidoscopy every five years and colonoscopy every 10 years. People with more risk factors may start screening earlier.
As with any disease, prevention is better than cure. We may not be able to prevent colorectal cancer with a 100 per cent success rate. However, we can reduce our risk of developing this disease with a diet rich in fibre, exercise and with maintaining a healthy weight. Early detection followed by prompt appropriate treatment greatly increase ones chances of successful treatment and cure.