Cancer of the Colon, Rectum & Anus

Dr Kingsley’s comments

Cancer of the large intestine is the second most common cause of death from cancer in the UK. It is a common cancer in many countries. It is more common in areas where the level of selenium is low in the soil and people eat food grown in that soil. There is also a familial incidence where people grow polyps in their bowel, which can turn malignant. There is also a hereditary form, which does not develop polyps.

There is an increased risk of developing cancer of the colon if a person has suffered from inflammatory bowel disease for a long time, and there seems to be an association with a high fat, low fibre diet. There has recently been a suggestion that a low dose of aspirin may be partially protective of bowel cancer, but the connection is insufficiently strong to justify its regular use in everyone because of aspirin’s undesirable effects in some people.

Signs and Symptoms.

Although cancer of the colon is usually eventually diagnosed after a person has complained of a number of symptoms, occasionally it is discovered when a routine sigmoidoscopy (a camera inserted up the rectum) is carried out because of a strong family history of colon cancer, there having been no symptoms at that stage. A common first indication that cancer may be present, or developing, is a change in bowel habits, i.e. the development of diarrhoea or constipation, or a mixture of both, when previously there had been normal and regular bowel movements.

A first symptom may be generalised abdominal discomfort, but sometimes the first sign is bleeding from the rectum, although that can also indicate piles. Colon cancer may eventually be found to be the diagnosis if someone has bled slowly for some time, without noticing it (or possibly ignoring it), and iron-deficiency anaemia develops. This may only be picked up because the person started to complain of feeling short of breath on only slight exertion, blood tests revealing the anaemia, which is then thoroughly investigated.

When the colon cancer is fairly advanced, the first obvious symptom or sign may be a swollen tummy, which, when it is examined, is found to contain a lot of fluid that should not normally be there. Before this stage, however, examination of the tummy may present a mass (a tumour), which is subsequently identified as being in the colon. Further tests diagnose cancer. For the condition to have reached these stages, it is likely that there were some indications that all was not well, but such symptoms can be quite mild and not really alarm the person sufficiently to seek medical advice.

In advanced disease, there may be an acute abdominal emergency, which needs immediate and urgent admission to hospital. This is when parts of the intestines have become so blocked by the tumour that food cannot pass through them. The symptoms then include severe abdominal pain and vomiting. The condition is not surprisingly called ‘intestinal obstruction’.

Another way colon cancer can present in an advanced stage is if the tumour grows in such a way that the bowel wall breaks down and contents leak out into the surrounding tissues. This can be extremely painful because the bowel has ‘perforated’, the contents being very irritant and inflammatory to the local area. Anyone who has suffered from a perforated appendix will know how painful it can be.

If the cancer is in the rectum, two other symptoms will most likely occur, namely tenesmus (a feeling of discomfort, tightness or spasm in the rectum) and a feeling of not emptying the bowels completely at each evacuation, because, of course, there is still ‘something there’.

Investigations.

In the early stages, endoscopic examination (a camera inserted into the rectum) is the most likely first step after the usual examination (including what is known as a rectal examination, when the doctor inserts a finger in the rectum) and routine blood tests, especially liver function tests. A biopsy will almost certainly be taken to confirm the diagnosis.

A barium enema may also be carried out, especially if the tumour has created a stricture that stops the endoscope passing as far as the surgeon would like. This will be done to see if there is more than one tumour, i.e. a second tumour in another part of the colon, as this will probably alter the recommended treatment.

Additional tests will include a chest X-ray, as secondaries often spread to the lungs. As they are more likely to spread to the liver, an ultrasound scan will be done of the liver. Finally a CT scan will be done on the abdomen to see if there are any secondaries anywhere within the abdominal cavity. The result of all these tests will help the Oncologist decide on what he considers to be the best treatment regime. An MRI scan may be more appropriate in cancer of the rectum to look for any local spread.

When the situation is not clear from any investigations, a surgeon may do what is called a laparotomy, when he opens the bowel ‘to have a look inside’. Sometimes this is the first time cancer of the colon is discovered, especially in a younger person with an ‘acute abdomen’ when cancer is not suspected.

Conventional Treatment.

Surgery to remove the tumour and any local lymph glands that seem to be involved is the first consideration, provided it is practical. Surgeons nearly always ask permission to be allowed to create a stoma (an ileostomy or a colostomy), in case it is needed, although this can often be reversed at a later stage.

However, once the surgeon has opened up the abdomen, he sometimes finds the situation different from what the scans had suggested, so he needs to be able to do what he considers appropriate at the time. With the section of bowel having been removed, he then connects the bowel together again, in what is called an end-to-end anastomosis. It’s rather like plumbing two tubes together.

When the tumour is definitely in the rectum, the surgeon knows that a stoma will have to be created, as there will not be enough of the ‘tube’ of the rectum to join to the other end of the bowel. This is then a major operation requiring two teams of surgeons, called an ‘abdomino-perineal’, when the rectum will be completely removed and closed up.

Chemotherapy is used more often for cancer of the colon, either before or after any operation, than in cancer of the rectum, where radiotherapy is more likely to be undertaken, especially to reduce the risk of local spread of any cancer not removed at operation.

Surgical removal of liver secondaries is often undertaken, if there are not too many of them, they are accessible and a reasonable amount of liver will be left. The liver has a remarkable ability to expand after quite a lot of it has been removed.

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