Colon cancer is one of the most common types of cancer in the developed world. Here we answer some frequently asked questions about Colon Cancer symptoms, causes and treatments.
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Q. What are the bowels?
A. The bowels are the intestines: the section of your digestive system between the stomach and the anus. The small intestine comes first, running down to the appendix. The rest of the digestive system is the large intestine, which is divided into the longer colon and a short rectum, just before the anus.
Q. What is bowel cancer?
A. Bowel cancer is the term commonly used to describe colo-rectal cancer – cancer of the large intestine, which is composed of the colon and rectum. Two thirds of these cancers occur in the colon and one third in the rectum. Cancers of the small intestine are quite rare.
Q. How common is bowel cancer?
A. Bowel cancer is one of the most common types of cancer. There are about 40,000 cases in the UK each year, 143,000 new cases in the USA, 23,000 in Canada and 14,000 in Australia. More than 80% of these are in people over 60. The average person has a 1 in 20 chance of being diagnosed with bowel cancer at some time in their life.
Q How dangerous is bowel cancer?
Bowel cancer is the second most common cause of cancer death (after lung cancer) in the most western countries. It causes about 16,000 deaths a year in the UK, 51,000 in the USA, 9,000 in Canada and 4,000 in Australia.
Causes / Risks /Symptoms
Q. What causes bowel cancer?
A. There is no identified cause of bowel cancer, but it is known that most cancers in the bowel begin as polyps – small, wart-like growths on the inner surface of the intestines. These polyps are very common – a third of people have them – but only a tiny fraction of them develop into cancer.
Q. Who is at risk of bowel cancer?
A. Like most cancers, the risk of bowel cancer is higher amongst the older population. In western countries, more than 80% of bowel cancers are diagnosed in people over 60. Obesity can increase the risk of cancer of the colon by up to one third. High alcohol intake is also known to increase the risk of bowel cancer. However, the regular use of some common medicines, such as aspirin-like painkillers and hormone replacement therapy, are known to reduce the risk of bowel cancer.
Q. Is diet linked to bowel cancer?
A. Diets high in red meat and processed meats are associated with a higher risk of bowel cancer. However, diets high in fibre, vegetables and fruit have been shown to reduce the risk.
Q. Does bowel cancer run in families?
A. Having a close relative (parent, brother, sister or child) diagnosed with bowel cancer doubles your own risk of getting it. Your risk will be even higher if that relative is under the age of 50 when diagnosed, or if you have more than one close relative who is diagnosed. If you are concerned, speak to your doctor.
There are a very few families with genes that give a high, sometimes very high, chance of getting bowel cancer. These genes are responsible for about one in five cases of bowel cancer. One or two of these genes carry such a high risk that the people with them are almost certain to get bowel cancer unless they have preventative treatment.
Q. What are the symptoms of bowel cancer?
A. There are a variety of known symptoms of bowel cancer including anaemia, blood in the faeces, lasting diarrhoea or constipation, abdominal pain, or even a blockage of the bowel. However, the symptoms vary from case to case and some cases do not cause any symptoms at all. All the known symptoms of bowel cancer (apart from blockage of the bowel) can also be caused by more common and less serious conditions.
Diagnosis/Testing/Screening
Q. How is bowel cancer diagnosed?
A. Colonoscopy is used to visually examine the inside of the colon and rectum. This requires the bowel to be completely empty, so you have to maintain a light diet and take laxatives for two days before. After having a sedative to relax you, a long flexible fibre-optic tube is passed into the anus and up the bowel. During this procedure, tiny tissue samples (biopsies) can be taken from any suspect parts of the bowel wall. Also any polyps (see ‘What causes bowel cancer’ above) can be removed.
Another useful method of diagnosis is a barium enema. The bowel also needs to be empty for this, so the same diet and laxative preparation is required. A tube is inserted into the anus and the colon filled with a solution of barium, which shows up as white on an X-ray. This X-ray gives an accurate picture of the shape of the inside of the bowel.
Other techniques such as CT scanning or ultrasound can also be used to diagnose how advanced the cancer is.
Q. Is early diagnosis important?
A. Early diagnosis is very important. If the cancer is still at an early stage when discovered, it can be cured by surgery in the vast majority of cases. However, very few of the patients diagnosed with advanced bowel cancer which has spread to other organs live more than a few years.
Q. What tests can be used to detect bowel cancer?
A. Apart from a colonoscopy (see diagnosis, above) there are no simple tests which are specific for bowel cancer. However, there are tests for the presence of small amounts of blood in the faeces, which is a good indication that further tests are advisable.
Q. Is there screening?
A. Some countries, ie Australia and UK, have a national screening programme in which people over 50 or 60 are sent a home kit that they can use to send off a tiny sample of faeces that is then tested for the presence of any blood. Those people who test positive are given an appointment with a nurse or doctor to determine if they should have a colonoscopy.
Treatment
Q. Can bowel cancer be cured?
A. Yes, if diagnosed early enough, treatment will usually give a long-term cure.
Q. How is bowel cancer treated?
A. Surgery is the main method of treatment. The part of the bowel containing the tumour is chopped out. Sometimes, the remaining ends of the bowel can be joined straight back together. If not, a colostomy is performed: the ‘working’ end of the bowel is diverted to the surface of the abdomen, where the faeces are collected in a plastic bag. Sometimes this is a temporary measure and when the other part of the bowel has recovered it can be reconnected to the rest of the bowel. However, if the tumour is in the lower rectum, then both the rectum and anus have to be removed and the colostomy will be permanent.
Depending on how advanced the cancer is, patients are often given chemotherapy, or sometimes radiotherapy, after the operation as this can kill off any remaining cancer cells.
Q. What newer treatments are available?
A. A number of new drugs have been developed and are being evaluated to find out whether they are better than the current drugs and which patients they help the most.
Q. What are the side effects of treatment?
A. Surgery, of any sort, causes tiredness and some pain, but these pass. The long-term side effects of a colostomy are described above. The main side effects of chemotherapy can be thinning or loss of hair (which only happens with some drugs and is temporary), tiredness, diarrhoea, nausea, sore mouth and minor infections. These all stop when the treatment stops. Radiotherapy has some similar side effects (tiredness, diarrhoea and nausea) and some different ones: red and sore skin where the treatment was given and bladder inflammation, causing frequent and uncomfortable urination.
Q. How effective is the treatment?
A. If diagnosed early, when the tumour is still limited to the inner layer of the bowel, these treatments are very effective, with more than 90% of patients alive five years after diagnosis. However, if the cancer has spread to the edge of the bowel at the time of diagnosis only about half of the patients survive for this long. Once the tumour has spread beyond the bowel to other organs, it is normally incurable. Only one in thirty of these patients survive for five years.
Sources of Information
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