Colorectal cancer is a general term applied to malignant tumours occurring anywhere within the colon (large bowel or large intestine). This includes the rectum which is the last part of the colon before the anus. Colorectal cancer is the second highest cause of cancer death in the in the UK (behind lung). Most cases occur in people over 50 and if colorectal cancer is diagnosed at an early stage, there is a good chance of a cure. For this reason is it important to recognise the possible symptoms of the disease.
Although colorectal cancer can develop for no apparent reason, there are certain risk factors which increase the chance that colorectal cancer will develop. It is important to know if there is a family history of colorectal cancer. Some families carry faulty genes that predispose to the development of colonic polyps which can latter develop into cancers. The greater the number of near relatives who have had colonic cancer particularly at a young age the greater the potential risk. Once a family is identified then members of the family can be screened by looking into the bowel with a flexible ‘telescope’ called a colonoscope. Certain lifestyle factors can also increase the risk of colorectal cancer including obesity, eating a lot of red meat, drinking a lot of alcohol and smoking.
When a colorectal cancer first develops it usually causes no symptoms.
As it grows, the symptoms that develop can vary, depending on the site of the tumour. Initially symptoms are caused by one of two things. Firstly the tumour is more fragile than normal tissue so it bleeds easily. Secondly the tumour starts to disturb flow of faeces through the bowel. Thus the most common symptoms are passing blood and a change in bowel habit particularly a change towards looser more frequent bowel motions. The further the tumour is from the anus the more the blood is changed by the bowel. The faeces may just look darkened or the patient may not notice any obvious change. As blood is lost the patient may become anaemic. Thus they might look pale and easily become short of breath and fatigued. If the tumour is in the rectum the patient may feel as if they are not emptying their bowels properly. Tumours like these, close to the anus, usually cause visible bleeding. Occasionally, a patient may feel a lump in their abdomen. However it is more common for the GP to find the lump in a patient who is experiencing the symptoms of anaemia. Cancers also cause some general symptoms of malaise. These include weight loss, lethargy and loss of appetite. More rarely colorectal cancers present as emergencies when the bowel has become completely blocked or has burst. These patients have usually had the symptoms described above for some time but have not sought medical advice
Do not ignore these kinds of symptoms. For most patients, another cause for the symptoms will be found – for example haemorrhoids or diverticular disease. However some patients will have a colorectal cancer.
If the tumour can be operated on, then the chances are very high that a patient will be cured of the disease. The most important investigation for a patient suspected of having a colorectal cancer is a colonoscopy. This is a flexible telescope examination of the colon. These tests are routine and very safe. It requires a visit for half a day to the hospital. The day before the test, the patient is given a strong laxative to take at home. This cleans the colon out. The examination itself involves a couple of injections which take away the discomfort of the test. Many patients do not remember much about the investigation. For most patients the test will show that there is no cancer in the bowel. Some patients will have polyps and these are removed to prevent them becoming a cancer in the future. A small number of patients will have a colorectal cancer. These patients will be carefully counselled about the findings and further tests including a body scan (CT scan) will be arranged. From here, care will be managed by a team of specialists who work closely together to make sure the very best outcome is achieved. Most patients will be initially treated by removing the cancer surgically. New techniques mean that these operations are now commonly performed using keyhole techniques. This results in faster recovery and less pain. Only a very small percentage of patients need to have a ‘bag’ or colostomy. For the majority the bowel is reconnected and bowel function returns to normal. Some patients may require additional treatments such as chemotherapy and radiotherapy.
Early diagnosis and treatment of colorectal cancer gives excellent results.
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