Colorectal Cancer
What is colorectal cancer?
The colon and rectum make up the large intestine, which is part of the digestive system. Most of the large intestine is made up of the colon; the different parts of the colon are described below:
- The first section, known as the ascending colon, extends upward on the right side of the abdomen.
- The second section, known as the transverse colon, goes across the body from the right to the left side.
- The third section, known as the descending colon, descends (travels down) on the left side.-
- The fourth section, known as the sigmoid colon, joins the rectum, which connects to the anus.
The ascending and transverse sections of the colon together, are called the proximal colon. The descending and sigmoid colon are called the distal colon.
The colon is where the body extracts water and salt from the remaining food or waste matter. The waste then moves through the rectum and exits the body through the anus.
Most colorectal cancers start as a growth, called a polyp, on the inner lining of the colon or rectum. Some types of polyps can change into cancer over time, usually after many years. The different types of polyps are:
- Adenomatous polyps (adenomas): These polyps sometimes change into cancer and are therefore refer red to as pre-cancerous polyps.
- Hyperplastic polyps and inflammatory polyps: These polyps are more common and generally do not develop into cancer.
- Sessile serrated polyps and traditional serrated adenomas: These polyps have a high risk of developing into colorectal cancer.
Screening helps to detect cancer in people who have no symptoms of the disease. Regular colorectal cancer screening is one of the most powerful weapons against colorectal cancer .
Screening can often find colorectal cancer early, when it’s small, hasn’t spread, and might be easier to treat. Regular screening can even prevent colorectal cancer. A polyp can take as many as 10 to 15 years to develop into cancer. During the screening procedure, doctors can detect and remove polyps before they become cancerous.
Metastatic colorectal cancer
Metastatic colorectal cancer occurs when the cancer cells within the tumour have spread from its original location to other parts of the body.
The wall of the colon and rectum is made up of many layers. Colorectal cancer starts in the innermost layer (the mucosa) and can grow outward through some or all the other layers. When cancer cells are in the wall, they can grow into blood vessels or lymph vessels and travel to nearby lymph nodes or to other parts of the body.
Regardless of where a cancer may spread, it’s always named for the place where it started. For example, colorectal cancer that has spread to the liver is called metastatic colorectal cancer, not liver cancer.
