Colon Cancer Diagnosis London

What are the symptoms of Colon Cancer?

The symptoms of a colon cancer are not specific and can be as simple as a slight change in your usual bowel habit e.g. becoming a little constipated or loose. Rectal bleeding is a common symptom in those with a cancer in the rectum or sigmoid colon (the last parts of the bowel) as is a feeling of needing to open your bowel but without much or anything being passed. When a cancer affects the upper parts of the colon (especially the caecum or ascending colon) there may be no symptoms from the bowel and anaemia (due to silent bleeding) and weight loss can be the presenting complaint. Unfortunately, most colon cancers have no symptoms until the tumour is large enough to alter the passage of stool in the colon – at this stage, the cancer is highly likely to have spread making a cure much less likely. This emphasises the importance of screening the at risk population and appropriate investigation of anyone over 55 with symptoms, even if these might seem trivial.

How is colon cancer diagnosed?


The best test for diagnosing colon cancer remains a colonoscopy. This involves passage of a flexible endoscope around the colon via the anus, all the way to where the small intestine joins the colon (at the ileo-caecal valve in the caecum, near the appendix). Many people think this test sounds rather awful but, in fact, most of this is the fear of the unknown and the test is both quick, involves only mild discomfort and, importantly, is highly accurate. It does, however, need preparation beforehand to clear the bowel of faeces (as do all tests of the colon, inevitably) so that good views are obtained. This preparation involves taking laxative solutions which cause a lot of diarrhoea. The test itself is done with mild to moderate sedation, mainly to relax the patient and minimise any discomfort, particularly whilst the left side of the colon is examined. Later in the procedure, when the right colon is being examined and when the endoscope is being withdrawn, the patient is quite awake and watching the inside of the colon on the television screen.

Colonoscopy is a highly accurate test, particularly for the exclusion of colon cancer and colonic polyps. Moreover, polyps can be safely removed at the time of colonoscopy (by various techniques) and progression to colon cancer therefore prevented. Colonoscopy is also used for the assessment of other symptoms and situations, particularly for looking for Crohn’s disease and ulcerative colitis in younger individuals presenting with persistent bowel symptoms.

The risks of colonoscopy, particularly when purely a diagnostic colonoscopy, are very low. Perforation of the colon is the most talked of complication but in a diagnostic colonoscopy the risk is around 1 in 1000 cases or lower. In more difficult cases, for example, when larger polyps are being treated, the risks are increased, but these are balanced against the benefits of having such polyps treated successfully and surgery avoided. Your doctor will always discuss such risks with you prior to undertaking the examination.

Other colon tests

There is a lot of interest in the role of using CT scanning and MRI scanning to image the colon. These have the advantage of not needing an endoscope but the disadvantage of still needing the bowel preparation and not having the capacity to treat any polyps or other findings if present. The accuracy, however, of these tests is now very good and time may certainly see CT or MR colonography becoming routine in colon cancer screening. A flexible sigmoidoscopy is essentially half a colonoscopy. It is an endoscpic examination of the left colon, via the anus, but because only the left side is being examined, the patient has only an enema before the examination (to clear the left colon of faeces). No oral laxative preparation is needed. This test is often preferred when bright red rectal bleeding is the only symptom. Red blood is unlikely to have arisen higher than the left side of the colon so the test is highly likely to detect any polyp or cancer if this is the cause of the bleeding (most frequently, bright red bleeding comes from haemorrhoids). In fact, 80% of colon cancers occur in the left side of the colon, so a flexible sigmoidoscopy is also a good screening test for colon cancer. Colonoscopy, however, comes with the reassurance of knowing the whole colon is normal.


How do I get treatment?

To get further information or treatment, please contact one of our consultants at The London Bridge Digestion centre, on:

tel: +44 (0) 20 7403 3814