There is also evidence that patients who regularly take anti-inflammatory drugs, such as aspirin, may be at a lower risk of developing cancer, but at the moment it is felt that the potential risks of taking aspirin regularly outweigh the benefits. A diet rich in fresh vegetables and fruit and plenty of fibre seems to help protect against bowel cancer and there is some evidence that a diet containing much meat may increase the risk. There is also evidence that patients who regularly take anti-inflammatory drugs, such as aspirin, may be at a lower risk of developing cancer, but at the moment it is felt that the potential risks of taking aspirin regularly outweigh the benefits. Often a bowel cancer causes no symptoms at the beginning. If small amounts of bleeding go on for some time, anaemia may cause tiredness and decreased ability to work and exercise.
Weight loss is usually a late symptom.
Sometimes a cancer can perforate a hole through the bowel wall, so that bowel contents leak into the abdomen. This causes severe pain and the need for urgent surgery. A small tube is placed in the anus and the liquid barium and some air are introduced, with the patient on the x-ray table. The barium outlines the bowel and X-rays are taken to show any irregularity in the bowel wall caused by the cancer. Secondly, an examination can be made with a flexible telescope passed up from the anus.