Bowel cancer may also be called rectal, colorectal or colon cancer.
It is the UK's third most common cancer, with more than 35,000 cases diagnosed in 1999.
It is not easy to treat, mainly because it is often detected only once well-established - and possibly spread beyond the bowel itself.
Doctors urge the public to be more aware of the warning signs of bowel problems, and report them promptly to doctors.
However, estimates suggest that nine out of 10 bowel cancers detected early can be successfully treated.
However, once the cancer has spread beyond the wall of the bowel, it becomes harder to treat.
Professor David Kerr, from the University of Oxford, said: "Surgery still remains the only definitive and perhaps curative treatment - sadly though, in half those patients who have that operation, the cancer will come back.
"By the time patients present with the bowel cancer, which can remain hidden for many years, there can be tiny seeds of the cancer which have spread beyond the bowel."
The problem with bowel cancer symptoms is that they could easily be caused by something less life-threatening.
* rectal bleeding
* a change in bowel habit
* a feeling that you need to empty your bowels even when you have just been to the toilet
* abdominal pain
These symptoms are not uncommon - and could be a sign of something far less serious.
However, doctors advise that if such symptoms persist for longer than a couple of weeks medical attention should be sought.
Often, a GP will carry out a "rectal examination" to check for any abnormal changes.
This involves putting a gloved finger in the rectum - this should be a painless procedure.
To investigate these symptoms, doctors often ask patients to undergo sigmoidoscopy or colonoscopy.
Both these procedures involve inserting a probe into the bowel. This has a tiny camera on the end which allows the doctor to look for cancerous areas on the bowel wall.
This can be uncomfortable, but is very seldom a painful experience.
Sometimes a dye which shows up on x-rays is injected into the lower bowel to help doctors spot signs of cancers.
Doctors may order more tests, such as CT scans, to check to see if the cancer has spread to involve other organs such as the liver.
In November 2002 the government announced the foundation of a national screening programme for bowel cancer, which is now well underway.
This could be carried out either with sigmoidoscopy, colonoscopy or fecal occult blood tests, which involve taking a stool sample which is then checked for signs of bleeding.
There is believed to be a genetic link to a small number of bowel cancer cases, as those with a family history are more likely to develop it themselves.
However, diet is a key factor identified by scientists - certainly the low fibre, high fat diets favoured in the Western world are thought to have increased the rates of bowel cancer.
People are encouraged to eat plenty of fresh fruit and vegetables, as this appears to reduce the risk.
An increase in fibre in the diet has also been linked to a reduced risk of bowel cancer.
The main option for treating bowel cancer is surgery , and if the disease can be caught before it breaks through the bowel wall, the patient's chances are much higher.
In these cases, further treatment may not be necessary. This operation is called a bowel "resection" by doctors.
However, once the cancer has spread beyond the bowel, chemotherapy is used.
Radiotherapy is sometimes given if the cancer is inoperable, or perhaps to shrink a tumour to make an operation easier.