What Is Colorectal Cancer?

Colorectal Cancer, also known as bowel cancer, develops in the colon or the rectum (the large bowel or the large intestine).

The colon and rectum are part of the gastrointestinal (GI) or digestive system. Whilst the first part of the digestive system processes food for energy, the last part (colon and rectum) absorbs fluid to form solid waste (stool) that leaves the body.

The colon is about 1.5 meters long and has four sections:

• Ascending colon that starts with a small pouch (caecum) where the small bowel attaches to the colon and extends upward (for that reason it is called ascending) on the right side of the abdomen.
• Transverse colon goes across the body, from the right to the left side in the upper abdomen
• Descending colon continues downward on the left side
• Sigmoid colorectal is the last section so named because of its “S” (sigmoid) shape

The wall of the colon and rectum are made up of several layers.

The majority of colorectal cancers begin as a small growth on the bowel wall – a colorectal polyp or adenoma. These often times mushroom-shaped growths are usually benign, but some develop into cancer over time. If left untreated, it can grow into the muscle layer underneath, and then through the bowel wall.

Invasive cancers that are confined within the wall of the colon (TNM stages I and II) are often curable with surgery, usually over 90% of patients diagnosed at this stage will survive the disease beyond 5 years. However, if left untreated, the cancer can spread to regional lymph nodes (stage III).

Around 50% of patients diagnosed at this stage survive the disease beyond five years. Cancer that has spread widely around the body (stage IV) is usually not curable, with only 10-20% of patients surviving beyond 5-years. Colorectal cancer affects both men and women of all racial and ethnic groups.

The taboo surrounding cancer and in many countries the embarrassement of colorectal cancer contributes to the late diagnosis of the disease. There is often a lack of understanding of the symptoms, the risks and the prevention of the disease. In many countries there is also a low awareness of treatment choice and patient options. Above all in many European countries there is severe underfunding for the treatment of cancer. Colorectal cancer is one of the most highly treatable of all the gastrointestinal cancers and with early diagnosis and effective treatment people can live with colorectal cancer.

Click here to read the ‘What is Colorectal Cancer’ leaflet.