Why am I hearing more of colorectal cancers?
Cancer of the colon and rectum is now the commonest cancer in both men and women combined. Singapore has the highest incidence in SE Asia and even higher than Asian populations in Los Angeles and Honolulu. The annual incidence increases at a rate of about 2.5% a year, and results in about 1200 new cases a year and more than 400 deaths. Colorectal cancer awareness has become a priority in healthcare.
What causes colorectal cancer?
The exact cause is unfortunately still unknown. Unlike cervical or nasopharyngeal cancers it is not associated with any viruses. The link between high meat and fatty diet with colorectal cancer is weak and not firmly established. While 90% of colorectal cancers are sporadic and of unknown cause, 5-10% are known to occur within families and have a genetic component. Doctors also recognize the fact that cancers can arise from polyps within the colon and rectum. There is a polyp to cancer sequence and hence all polyps must be removed when detected during colonoscopy. Certain chronic inflammatory bowel diseases put a person at high risk for cancer but these are fortunately rare in our population.
What are the symptoms and signs of colorectal cancer?
Early symptoms include painless bleeding during bowel movement. The blood is frequently stale and mixed with stools. Some patients may experience sudden prolonged constipation or diarrhoea. Some may complain of mucus-like discharge from the anus. Late symptoms include abdominal distension and difficulty in defecation, nausea and vomiting. Pain is a late symptom and frequently heralds an advanced cancer.
So how do I prevent colorectal cancer?
As colorectal cancer has no exact known cause, the only way is through awareness and screening. Everyone should understand the early signs and symptoms and seek medical advice when they experience such symptoms, especially if they are above the age of 50 years old. Knowledge of any significant family history is also important. Currently, the most accurate way to detect colorectal cancer is fiber-optic colonoscopy.
When should I go for a colonoscopy?
Patients with symptoms suggestive of colorectal cancer should be evaluated with colonoscopy immediately. People with no symptoms or family history of colorectal cancers should be screened at the age of 50 years and ideally with a complete colonoscopy. Patients with a family history of colorectal cancers or polyps, or with a history of inflammatory bowel diseases should be screened earlier. Ask your doctor for details.
What is CEA and what must I do if it is found to be raised in a blood test?
CEA stands for Carcinoembryonic Antigen. It is a type of cancer marker. It is frequently raised in colorectal cancers. Unfortunately it can also be raised in many other non-cancerous conditions like chronic lung diseases and cirrhosis of the liver. It can also be raised in smokers. Furthermore CEA can also be normal value in patients with cancers. As it is not specific for colorectal cancer, its use as a screening tool cannot be justified.
How many stages of colorectal cancers are there and what do they mean?
There are four stages of colorectal cancer: A,B,C and D. Stages A and B mean the tumor is still limited to the wall of the colon. This also means that the chances of cure are higher and surgery is usually sufficient. Stage C is a critical stage and means that the cancer cells have spread to the surrounding lymph nodes and therefore potentially beyond. This means chemotherapy to control the spread is now necessary. Survival is also lower at Stage C. Stage D means the cancer has spread beyond the lymph nodes into the liver, lungs and bone. Cure is very much more limited now and chemotherapy can only prolong life to a certain extent. The Stages are determined after surgery when the resected specimen is sent to a pathologist for examination under a microscope. The surgeon cannot see if the lymph nodes are involved with his naked eyes during surgery.
How are colorectal cancers treated?
Surgery to remove the tumor is still the mainstay of treatment for colorectal cancers. This holds true even for Stage D cancers as the primary tumor if left behind can still cause problems during chemotherapy. In selected cases, laparoscopic (key hole) surgery may be offered for smaller incisions and faster recovery and discharge from hospital.
Once the lymph nodes are found to be involved (Stage C), the patient will be referred to an oncologist to commence chemotherapy after recovery from surgery.
What is a stoma?
A stoma is a loop or segment of bowel that is brought out through the body. Its purpose is to divert feces away from the cancer operation site to protect the area where the bowels have been joined together. Temporary stomas are easy to look after and easily concealed underneath clothing. It does not smell. After 3-6 months it can be closed. When the cancer involves the anus muscles, the anus has to be sacrificed and then the patient will have a permanent stoma. Again this is easy to look after and the patient can have an active and good quality life after surgery.
So what is the take home message for this important cancer?
Early colorectal cancers have minimal or no symptoms. Awareness and screening is key. Colonoscopy remains the gold standard for screening for colorectal cancers. Colorectal cancer if detected early has good outcome and a high chance for complete cure.
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