Large Bowel Cancer

Bowel cancer is the third commonest cancer in the world. Diagnosing and treating it early costs individuals and countries considerably less. The early diagnosis is made by colonoscopic examination.

If blood comes in the stool for no reason at all, if there is weight loss together with complaints of diarrhoea and constipation, or if there is a family history of colon cancer or polyps, a specialist in gastroenterology should be seen without fail and a colonoscopic examination carried out.

They arise most often from polyps inside the bowel. (Note: three quarters of polyps are benign and a quarter are malignant, and of the malignant ones a very small proportion turn into cancer after 7–8 years.) For this reason, if polyps are seen during colonoscopy they should without fail be taken out by polypectomy.

The first two pictures show a cancerous mass closing off the lumen of the large bowel. The last picture shows an ulcerated cancerous mass beginning 10 cm up the rectum, in a patient who came with the complaint of blood coming from the back passage.

When should colon cancer screening start?

Large bowel cancer is a disease that can be treated successfully when it is caught early, and in some cases it can be prevented by removing polyps.

According to current international recommendations, screening should start at age 45 for people at average risk. If the colonoscopy is normal and there are no other risk factors, it is usually repeated after 10 years.

People with large bowel cancer in the family, or who carry an inherited risk, may need to start screening earlier.

If you have rectal bleeding, unexplained anaemia, weight loss or a lasting change in bowel habit, do not wait until you are 45. In that case what is needed is not screening but an assessment to find the cause of the complaint.