How common is bowel cancer?

Bowel cancer is a major problem in Australia. Apart from skin cancer, it is the most common cancer affecting both men and women. About 10,600 people are diagnosed with bowel cancer each year, it is becoming a little more common, especially in men. About one in 18 men and one in 26 women will develop bowel cancer before the age of 75. The older you are, the greater your chance of developing bowel cancer — it affects mainly people over 50 but can occur at any age. Some people who develop bowel cancer inherit faulty genes from their parents but, for most people, age and diet contribute to developing bowel cancer.

How bowel cancer starts

Bowel cancer seems to start in two ways.  It grows from the inner bowel lining, and grows from a small raised area that looks like a mushroom and is called a polyp. These polyps are usually harmless (benign) but some polyps can become cancerous (malignant) and spread. If you have already had bowel cancer, polyps increase your risk of developing a second cancer.

Finding bowel cancer early

Bowel cancer spreads (metastasises) outside the bowel if it is not treated. It spreads fairly slowly and can stay in the bowel for months or years before moving outside it, first to the lymph nodes, then to other organs. This gives doctors a chance to remove and cure the cancer using surgery.

Lymph nodes are more commonly known as glands. We have them in many parts of our body and can feel them in our neck, groin and under arms. We also have them around our bowel. Bowel cancer is highly treatable when detected early, even if it has spread to nearby lymph nodes. When it has spread to other organs, such as the liver, many treatments can help, but a cure is more difficult. That is why it is so important to detect bowel cancer early, before it has spread to other organs.

Stages of bowel cancer

Your chance of cure depends on the stage at which your cancer is diagnosed.  One way to describe the stages of bowel cancer is listed below:

• Stage A cancer is confined to the bowel wall
• Stage B cancer has spread to the outer surface of the bowel wall and not beyond
• Stage C cancer has spread to lymph nodes outside the bowel wall and not beyond
• Stage D cancer has spread to liver and bones

Prognosis

The sooner bowel cancer is diagnosed, the better the likely outcome (prognosis). Survival statistics have shown that 88% of people with stage A bowel cancer and 70% of people with stage B bowel cancer will be alive five years after their diagnosis.

Overall, about 56% of people who have had their bowel cancer successfully removed are alive five years after their diagnosis. But these survival statistics represent the average number of people alive five years after their diagnosis and do not represent a single person’s chance of survival.

Many factors influence a person’s prognosis and it is best to talk to your doctor about your own situation. Although it is not a hard and fast rule, bowel cancer is unlikely to come back in people who are well and have no signs of it after five years.