Colon Cancer FAQs

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 is colon cancer?

A. Colon cancer is the term commonly used to describe colo-rectal (or bowel) cancer. The colon is part of the intestines. These consist of the small intestine (the section between the stomach and the appendix) and the large intestine (from the appendix to the anus). The large intestine is divided into the long colon and a short rectum, just before the anus. Two thirds of these cancers occur in the colon and one third in the rectum, with very few in the small intestine.

Q. Who is at risk of colon cancer?

A. There are about 106,000 new cases in the USA each year and 35,000 cases in the UK. More than 80% of these are 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 colon cancer. However, some common drugs, such as aspirin-like painkillers and hormone replacement therapy, are known to reduce the risk of bowel cancer.

Q. Does the diet affect the risk of colon cancer?

A. The risk of colon cancer appears to be linked to diet, although the evidence for which types of food are involved is not very clear. Low fat, high fibre diets appear to carry a lower risk. Greater consumption of vegetables and fruit has also been shown to reduce the risk. Increased consumption of red meat and processed meat has been linked to a higher risk. By comparison, eating fish does not appear to be a risk factor. Some evidence suggests that certain dietary supplements, such as calcium, selenium and, possibly, folic acid can reduce the risk.

Q. Does colon cancer run in families?

A. There are two inherited conditions which carry a substantially higher risk of colon cancer. In Familial Adenomatous Polyposis, affected family members develop thousands of small benign growths, called polyps, in the large intestine. Before the age of 40, one or more of these polyps will develop into a bowel cancer. In Hereditary Non-Polyposis Colorectal Cancer (also called Lynch Syndrome), patients develop cancer of the bowels and other organs, usually at an early stage. However, these conditions are very rare and only cause one in twenty cases of bowel cancer. Overall, the risk of bowel cancer doubles if you have a close relative (parent, bother or sister) with this cancer.

Q. Can we screen for colon cancer?

A. There are several ways in which we can screen for colon cancer. Checking for blood in the faeces is the simplest method, although there can be other reasons for this. A more accurate, but less pleasant method, is sigmoidoscopy, in which a flexible optical device is used to examine the inside of the rectum and colon. Both these methods of screening are currently being tested out in the UK to determine which is the best and whether such screening should be used for the whole population. Other screening methods are also being developed.

Q. What are the symptoms of colon cancer?

A. There are a variety of known symptoms of colon cancer including abdominal pain, diarrhoea and constipation, blood in the faeces, 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.

Q. How is colon cancer diagnosed?

A. Sigmoidoscopy (see above) or (the very similar) colonoscopy are used to visually examine the inside of the colon. Usually, a barium enema is used to take an x-ray 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. How is colon cancer treated?

A. Surgery is the main method of treatment. The part of the colon containing the tumour is chopped out and usually a colostomy is performed. In a colostomy, the 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 part of the colon that had the cancer 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. Often patients are given radiotherapy or chemotherapy after the operation as this can kill off any remaining cancer cells.

Q. What are the side effects of treatment?

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, before the tumour has spread from the bowel, these treatments are very effective, with about 90% of patients alive five years after diagnosis. However, if the cancer is advanced at the time of diagnosis (ie it has spread to the lymph nodes) only about half of the patients survive for five years.