Colorectal cancer is a term used to describe cancers (lumps, growths, tumours) of the colon (the large intestine or bowel) and rectum. Together, they are one of the most common cancers in the world. Tumours can be described as benign or malignant. Benign tumours do not spread, but malignant tumours, such as in colorectal cancer, are made up of cells that can spread to and damage other parts of the body.

If cells keep dividing when new cells are not needed, a mass of tissue forms. This mass of extra tissue, called a growth or tumor, can be benign or malignant.
Benign tumors are not cancer. They can usually be removed and, in most cases, they do not come back. Most important, cells from benign tumors do not spread to other parts of the body. Benign tumors are rarely a threat to life.

Causes

Researchers do not know the cause of colorectal cancer. But they do know that certain risk factors make it more likely that a person will develop the condition. These risk factors include:
Family history. About 10 percent of all cases of colorectal cancer are thought to be hereditary. People whose family members have had the disorder are more likely to contract it themselves.
History of colorectal cancer. Some people contract colorectal cancer more than once. New cancers develop in areas other than those in which the cancer first appeared.

Symptoms

The symptoms of bowel cancer are very similar to common complaints such as piles or irritable bowel syndrome. Blood in your stool may be a sign of cancer, but it can also indicate other conditions. Bright red blood you notice on bathroom tissue may come from hemorrhoids or minor tears (fissures) in your anus, for example.

When symptoms are present, some of the most common symptoms are:

* Rectal bleeding
* Changes in bowel habits.
* Stomach cramps or abdominal pain.

Diagnosis
Screening Tests: Early diagnosis depends on routine screening. The stool can be tested for occult blood. To help ensure accurate test results, the person eats a high-fiber diet that is free of red meat for 3 days before providing a stool sample. Alternatively, a doctor can test stool obtained during a digital rectal examination, in which a gloved finger is inserted in the person's rectum. If blood is detected, further testing is needed.

Treatment

Surgery – Surgery is an operation that involves removal of cancerous part of the colon. It acts as a primary treatment for colon cancer.
Biological therapy, also called immunotherapy, uses the body's immune system, either directly or indirectly, to fight cancer. The immune system recognizes cancer cells in the body and works to eliminate them. Biological therapies are designed to repair, stimulate, or enhance the immune system's natural anticancer function.

Chemotherapy – This treatment includes treatment with drugs that kills the cells, like cancer cells. This treatment is given to those with advanced cancers that have spread others parts of body, possibly outside colon.

Radiation therapy – Radiation therapy is a special kind of treatment, which uses radiation to destroy fast growing cancer cells.