Colon and Rectal Cancer

Colon and Rectal Cancer

What is colon and rectal cancer?

Cancer of the colon is one of the most common cancers in Ireland. It occurs in the bowel, which is also known as the intestine and includes the colon (large intestine) and the rectum, which is the lower six inches of the tract. In colorectal cancer, 70% of malignancies occur in the colon (the large intestine) and 30% appear in the rectum.

What causes colorectal cancer?

In most cases, the precise cause is unknown but there are a number of contributory factors which include:

  • A family history of colorectal cancer, polyps or inflammatory bowel disease. Approximately 5% of cancers of the colon occur in families with a predisposition to the disease.
  • It usually occurs in people over 50.
  • Women are at a slightly higher risk than men.
  • Those in industrialised parts of the worlds are more susceptible.
  • It is thought that a high-meat, high-fat, low-fibre diet encourages the production of carcinogens (cancer-causing substances).

What are the symptoms of colon and rectal cancer?

There may not be any symptoms initially. When symptom do occur, they vary widely depending on the location of the cancer within the large intestine. The first symptom may be an inexplicable change in the bowel habit, persisting for more than 10 days. Other symptoms may include: rectal bleeding, blood in the stool and abdominal pain. Some patients might only feel a general weakness and fatigue due to iron deficiency anaemia. Unexplained weight loss may also be noted.

Can colon and rectal cancers be prevented?

Prevention and early detection are the key to controlling and curing these cancers. Colorectal cancer begins as polyps, which are small, benign (non-cancerous) growths of cells that form on the inner lining of the colon. These polyps may grow larger over time and become cancerous, which is why if any polyps are found, it is usually advisable to have them removed before they can become cancerous.

Lifestyle changes can also reduce a person's chances of developing colon cancer. To reduce the risk of colon cancer, it is best to follow a diet that is low in fat and high in fruits, vegetables and fibre. It is also advisable to exercise regularly, to drink alcohol in moderation and for smokers to give up smoking.

Oestrogen replacement therapy may reduce the risk of colon cancer in postmenopausal women. Use of contraceptives is also thought to protect against the development of colon and rectal cancer.

How serious are colon and rectal cancers?

The outcome for colorectal cancers depends on the degree of spread of the tumour at diagnosis. Therefore, it is vital to see your doctor without delay if you are over 50 and have any symptoms which might suggest bowel problems.

The five year survival rate for those undergoing surgery for colon cancer is as high as 90% for cancers which have not spread to the lymph nodes. More than 50% of patients who have had a colectomy (surgery to remove the colon) survive in good health for more than five years.

Age is not a factor in treatment success. Treatment can prolong life, even when the cancer has spread.

How are these cancers treated?

Surgery is the most common treatment. For cancers that have not spread this often provides a complete cure. In most cases a partial colectomy (removal of a part of the colon) is performed. The cancerous tissue and a small amount of surrounding normal tissue are removed and the cut ends are rejoined to re-establish the channel. Chemotherapy and radiation therapy are often combined with surgical removal of the tumor to increase the likelihood of a cure.

Are there any long-term effects?

Naturally many patients who undergo treatment for colorectal cancer are concerned about preserving normal bowel, urinary and sexual function after treatment. Only a small minority of patients will need a permanent colostomy (an artificial opening of the abdomen used for the collection of wastes) following treatment.

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