Colorectal cancer

The article was written by MSc.Dr. Ha Thi Thu Hien - Laboratory Department - Vinmec Times City International Hospital

Colorectal cancer is a malignancy that starts in the colon or rectum, depending on where they start. Colon and rectal cancers are often grouped together because they have a lot in common.
Cancer begins to appear when cells in the body begin to grow out of control.
The colon and rectum make up the large intestine, which is part of the digestive system, it is a tubular about 1.5 meters long, consisting of 4 layers (mucosa, submucosa, muscle layer and serosa). The sections of the colon are named for the way food moves through them.
The first part is called the ascending colon. It begins with a bulging area called the cecum, where undigested food enters from the small intestine. It continues towards the right side of the abdomen.
The second part is called the transverse colon. It goes from the right side to the left side of the body.
The third part is called the descending colon because it goes down on the left side.
The fourth part is called the sigmoid colon because of its “S” shape. The sigmoid colon connects to the rectum, and then to the anus.
The ascending and transverse colon are called proximal colon. The descending colon and the sigmoid colon are called the distal colon.

The colon absorbs water and salt from the food that remains after it has passed through the small intestine. The substance that remains after passing through the colon will enter the rectum, the last 15cm long part of the digestive system. It is stored there until passing through the anus. The sphincter (also called the sphincter) around the anus keeps stools from coming out until they relax during a bowel movement.

Polyps in the colon or rectum
Most colorectal cancers start from a growth on the lining of the innermost layer of the colon or rectum. These tumors are called polyps.
Some polyps can turn cancerous over time (usually years), but not all polyps become cancerous. The likelihood of polyps turning into cancer depends on the type of polyp. There are different types of polyps.
Adenomatous polyps (also called adenomas): These polyps sometimes turn cancerous. Therefore, adenomas are called precancerous conditions. There are three common types of adenomas: tubular, villi, and tubular villi.
Hyperplastic and inflammatory polyps: These types of polyps are more common, but they are generally not precancerous. Some people with large (more than 1cm) hyperplastic polyps may need more frequent colon cancer screening.
Stemless serrated polyps and traditional serrated adenomas: These polyps are often treated the same way as adenomas because they carry a high risk of colorectal cancer.

Other factors that can put a polyp at risk of developing cancer or increase the risk of developing colorectal cancer include:
Polyps >1cm in size Multiple 3 polyps found Polyps with dysplasia

If cancer grows on a polyp, it can grow into the wall of the colon or rectum over time. The wall of the colon and rectum is composed of many layers. Colorectal carcinoma begins in the innermost layer (mucosa) and can grow outward through some or all of the layers of the colon wall (see figure below).

When cancer cells are in the layers of the colon wall, they can invade blood vessels or lymphatic vessels. From there, they can travel to nearby lymph nodes or to distant parts of the body.
The stage (level of spread) of colorectal cancer depends on how deeply the cancer cells have grown into the layers of the colon wall.
Vinmec International General Hospital is one of the hospitals that ensures modern equipment, a team of doctors, good and experienced staff with leading professors and doctors at home and abroad. Preventive, advanced tests allow the implementation of the most advanced colorectal cancer screening techniques.
If you have a need for consultation and examination at Vinmec Hospitals under the national health system, please book an appointment on the website for service.