Cancer can attack anyone indiscriminately, even those whose lifestyle is healthy enough. Cancer can appear on any part of the body because it comes from cells in the human body. So, there are many types of cancer that are found, one of which is colon cancer.
Almost all colon cancer begins in the mucosa, the innermost layer of the large intestine. To understand the diagnosis and plan for treatment, you must know first about the structure of the large intestine and how the development of colon cancer in the body.
Human large intestine structure
The intestine is formed from 5 layers. The first layer starts from the inside of the intestine or lumen. Lumen refers to an empty place or cavity. The first layer is where the absorption of nutrients, fat, and protein from the food we consume. This is also a layer that is biopsied in a colonoscopy.
The next layer is the muscularis mucosa which forms a barrier between the mucosa, and the third layer is called submucosa. Submucosa is rich in blood vessels that supply blood to the intestine and transports digested nutrients to other vital organs. The fourth layer is the muscularis propria, which acts to move food through the intestine, and the outer layer is serous.
What are the stages of development of colon cancer?
Colorectal cancer usually starts as a benign polyp that grows in the mucosa. Some people are more at risk of having polyps, especially those with a personal or family history of polyps and / or colorectal cancer, and those who carry genes specifically for inherited colorectal cancer. New research has also shown that people who have type 2 diabetes and those who are obese are also at higher risk of developing polyps and colon cancer.
Most polyps remain benign and are often termed hyperplastic polyps. The possibility of hyperplastic polyps turning into cancer is very low. Other benign polyps are sometimes referred to as pre-cancer. This polyp itself is not malignant, but has the possibility to become cancerous if not removed. Examples include adenomatous and hamartomatous polyps.
Adenomatous polyps that have tubular or villous characteristics have a greater chance of becoming cancerous. Adenomatous polyps and hamartomatous polyps are also types of polyps commonly associated with congenital colorectal cancer syndrome. The only truly malignant polyp is a polyp that has been proven to contain invasive carcinoma. Sometimes this carcinoma is limited to polyps, and sometimes attacks one or more layers of the intestine.
Adenomas usually grow creeper, resembling small mushrooms. Adenoma tend to grow slowly within a decade or more. The risk of adenomas developing into cancer increases with increasing size and growth in the intestine over time. At a very early stage, abnormal cells are contained in the polyp and can be removed easily by a colonoscopy before turning into invasive cancer.
However, as growth and division occur in the polyps, these cancer cells can eventually attack the closest intestinal tissue and outside the walls of the large intestine or rectum. If the cancer develops, the tumor will grow in all layers of the large intestine and rectum tissue, and can metastasize, spread cancer cells into the blood circulation system, and spread to other organs such as the liver and lungs.
How likely is the polyp to develop into colon cancer?
Less than 10% of all adenoma polyps turn into cancer. More than 95% of colorectal cancers develop from adenomas. Recent research has also shown that some polyps that have long been considered benign can also become cancerous.
For this reason, the doctor will remove all polyps during the colonoscopy screening. Small polyps are easy and painless to remove, because they are snared and cut with a wire coil that is passed through a colonoscope. Very small polyps can also be destroyed with a device that delivers heat to the polyp through a mild electric current. Very large polyps may require surgery, regardless of their benign or malignant nature.
Abnormal cell growth and inflammation can be other pre-cancerous conditions of colorectal tissue, and are called dysplasia. The abnormal area and inflammation of the polyps will be biopsied and sent to a pathologist who will examine the tissue forming the malignant cells. If it turns out to be benign, as is often found, no further treatment is needed, although doctors will recommend scheduling routine colonoscopy to monitor areas of the large intestine that appear abnormal.