Bowel cancer (also known as rectal, colorectal or colon cancer) affects the lower part of the digestive system and is the third most common type of cancer in men and the second most common in women. Two-thirds of these tumours develop in the colon or large bowel and about one third are in the rectum or anus.
The condition is rare in people under 40 and almost 85 per cent of cases are diagnosed in over 65-year-olds. While cancer of the colon affects men and women equally, cancer of the rectum is a little more common in men.
Bowel cancer isn’t easy to treat, mainly because it’s often detected once well-established – and possibly after it has spread beyond the bowel. However, estimates suggest that more than 90 per cent of cases can be successfully treated if detected early. Overall, survival has doubled over the past 40 years because of earlier diagnosis and better treatments.
Doctors urge the public to be more aware of the warning signs of bowel problems and to report them promptly.
Bowel Cancer Symptoms
The symptoms of bowel cancer may be hard to spot because less life-threatening compliaints, such as haemorrhoids or irritable bowel syndrome may also cause similar problems.
However, if the following symptoms persist for longer than a couple of weeks, medical attention should be sought:
- Blood in your faeces (stools or poo). This may be bright red or plum-coloured. This is the most commonly noticed symptom and should never be ignored. See your doctor urgently if there is significant blood loss
- The appearance of mucus in the faeces
- A change in your regular bowel habits, such as constipation or diarrhoea, that’s severe or lasts for two weeks or more
- Abdominal pain or discomfort that lasts for two weeks or more
- Persistent pain in the back passage or anus
- Unexplained weight loss
- Some people feel tired, dizzy or breathless because they’ve become anaemic from microscopic bleeding from the bowel
Bowel Cancer Causes
Like all cancers, bowel cancer results when there is loss of control of the growth of the cells – in this case the cells that line the inner surface of the bowel. Our genes control cell growth and so changes – or mutations in the genes – is central to cancer development. But, what causes these genetic mutations? Many genes are involved in controlling the growth of cells and so a series of genetic changes may be needed before a cancer forms.
Exactly how this whole process develops in bowel cancer isn’t known, but in a small number of cases, genetic mutations are inherited leaving a person at much greater risk. These people often have a family history of bowel cancer, occurring at a much younger age than usual. (Bear in mind that the vast majority of bowel cancers develop in later life). Two inherited conditions are known to increase the risk of bowel cancer.
These are Familial Adenomatous Polyposis (FAP) and a condition called Hereditary Non-Polyposis Colorectal Cancer (HNPCC or Lynch Syndrome). These are rare but responsible for about 5 per cent of all bowel cancers. In FAP multiple small non-cancerous growths or polyps develop in the colon, which may become cancerous over time. People with HNPCC are at increased risk of other cancers too, including womb, ovary, stomach, pancreas and bladder.
If you have a first-degree relative (a member of your immediate family) diagnosed before the age of 45 or two immediate family members affected by the condition at any age, you should talk to your GP about genetic screening to see if you’re at risk. Keep a record of your family health history.
Smoking, an inactive lifestyle, heavy alcohol intake (more than 4 units a day) and obesity all increase the risk of bowel cancer. Diet is another key factor identified by scientists. A high intake of processed foods, red meat, low-fibre and high-fat foods are thought to have increased the rates of bowel cancer.
Your risk of bowel cancer increases with age, as the average age of diagnosis is about 70. However, younger people can also be diagnosed with the disease. Previous problems with chronic inflammatory bowel disease, such as long standing ulcerative colitis and Crohn’s disease, also appear to increase the risk, as does diabetes and some other conditions.
Bowel Cancer Diagnosis
If you have symptoms that are causing you concern, see your doctor, who may want to do further tests to check for a diagnosis of bowel cancer. This may include a rectal examination to check for any abnormal changes at the lower end of the bowel. This involves putting a gloved finger in the rectum to feel for any lumps or swellings – this is usually only slightly uncomfortable. They may also arrange other tests including one known as “faecal occult bloods” or FOBs. This involves providing several samples of your faeces to check for microscopic amounts of blood lost from a tumour.
If faecal occult blood tests are positive, or to investigate bowel cancer symptoms further, doctors and hospital specialists often recommend a sigmoidoscopy or colonoscopy. Both these tests involve gently passing a long thin tube containing a tiny video camera through your back passage and into the rectum and colon to take a close look at the inside of the bowel. If polyps or abnormal areas of the lining of the bowel are seen, biopsies may be taken and sent to the laboratory for analysis. This can be uncomfortable, but is very seldom a painful experience. Less often, a barium enema may be done. This involves injecting a dye into the lower bowel via an enema, which shows up on x-rays to help doctors spot signs of cancers.
Bowel Cancer Treatment
If a diagnosis of bowel cancer is made, the tumour will then be staged. A system known as Dukes’ staging is usually used. Staging is important because it helps to predict how the cancer is likely to progress and which treatments are most appropriate. For example, more complex tests such as CT or MRI scans may be done to see if the cancer has spread to other organs, such as the liver.
As with most cancers these days, a team of specialists including doctors, nurses, radiologists, oncologists, radiotherapists and others then get together to review all the test results and then recommend a schedule of suitable treatment, which may include surgery, chemotherapy and radiotherapy and other treatments.
Bowel Cancer Resection
The main treatment option for bowel cancer is surgery – if the disease can be caught before it breaks through the bowel wall, chances of success are much higher.
Usually, the piece of bowel that contains the cancer is removed and the two open ends are joined back together. This operation is called a bowel resection, and it may cure early cancers that haven’t spread.
Bowel Cancer Stoma
If the two sections can’t be joined back together, often because the tumour is too low, the bowel can be brought out through the abdominal wall. This is called a stoma, which is connected to a colostomy bag. Although this procedure is more likely after removal of a tumour in the rectum, it isn’t always necessary and may only be temporary. In these cases, further treatment may not be necessary.
In a number of people, cells from the cancer may have already spread to form microscopic deposits or metastases in the lymph nodes or elsewhere in the body. These grow to form secondary cancers which need further treatment.
Colorectal Cancer Chemotherapy and Radiotherapy Treatment
Chemotherapy and, in some cases, radiotherapy are increasingly being used to treat colorectal cancer in addition to surgery, especially in more advanced tumours. Radiotherapy is not usually used in colon cancer but for example, a combination of radiotherapy and chemotherapy may be given before surgery for rectal cancer. This is known as neo-adjuvant therapy and may reduce the risk of recurrence and improve survival rates.
Chemotherapy may be used to destroy any cancer cells left behind after surgery, especially if the tumour has advanced past the earliest stage. This is called adjuvant chemotherapy. A number of different chemotherapy drugs may be used and several research studies are on-going to try to work out which ones are most effective.
Newer treatments known as biological therapies (which are based on natural immune system and signalling chemicals in the body) are also being tested in bowel cancer.
Bowel Cancer Survival Rate
How well patients do after treatment depends on the stage the cancer has reached. Survival rates have improved in the past 30 years, but overall survival is still only about 50 per cent at five years after diagnosis (bear in mind though that many bowel cancers occur in older people who may die for other reasons). However, when bowel cancer is caught early – before it has spread to other organs such as the liver or the lungs – the chances of recovery are much higher. Among those with Dukes’ A stage bowel cancer (the earliest stage) 93% survive more than 5 years.
Bowel Cancer Prevention
There are many things you can do to reduce the risk of getting bowel cancer.
Diet is very important. Eat plenty of fresh fruit and vegetables. Choose a high-fibre diet with plenty of wholegrain carbohydrates (pasta, bread and rice). Avoid or cut down red meat and keep saturdated fat intake as low as possible.
Moderate amounts of exercise may also protect against bowel cancer, and will help to control weight. Elsewhere, give up smoking and drink no more than moderate amounts of alcohol.
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