How does colorectal cancer spread and metastasize

In recent years, colorectal cancer has become one of the major diseases that endangers society and human health, and it has brought great pain and distress to humans. In order to reduce the incidence of colorectal cancer, we humans should understand the spread and metastasis of colorectal cancer:

1. Direct Infiltration The direct spread of colorectal cancer develops in the direction perpendicular to the longitudinal axis of the lymphatic vessels in the intestinal wall, that is, it infiltrates along the circumference of the intestinal tube and into the deep layer. The spread parallel to the long axis of the intestinal tube is rare, so it rarely exceeds 2~3cm above and below the tumor. Someone observed 236 cases of colon cancer pathological specimens and found that only 0.5% of the intestinal walls infiltrated beyond 4cm above and below the tumor. Direct spread can break through the serosal layer and invade adjacent organs such as the liver, gallbladder, bladder, uterus, vagina, etc. Or cause implantation and dissemination in the abdominal cavity.

2. There are three common planting methods:

(1) Peritoneal implantation: When cancer cells invade the peritoneum, they can fall off onto the surface of other organs in the peritoneal cavity, causing peritoneal implantation and metastasis. Peritoneal implantation and metastasis is a complex biological process. The most common sites include the greater omentum, mesentery, vesicorectal fossa, uterine rectal fossa, etc. It is more common near the pelvic pouch of Douglas (rectouterine pouch); it can be palpated in the vagina and become a nodule, or it can be widely implanted in the abdominal cavity, forming cancerous peritonitis.

(2) Intestinal implantation: There are often detached cancer cells attached to the intestinal cavity near the colorectal cancer lesions. When the mucosa is intact, cancer cells will not implant and grow. However, if the intestinal mucosa is damaged, implantation may occur at the damaged site. This may also be one of the reasons why colorectal cancer often has multiple lesions.

(3) Medical implants: They are usually implanted at the anastomosis and abdominal wall incision during surgery. Precautions should be taken during surgery to avoid them.

3. Lymphatic metastasis In recent years, ultrastructural studies on the colon mucosa have confirmed that there are no lymphatic vessels in the colon mucosa. Therefore, intramucosal cancer of the colon is unlikely to metastasize to lymph nodes, but if the lesion infiltrates below the muscularis mucosa, lymph node metastasis is possible. Zheng Zhitian pointed out that lymph node metastasis often begins after the intestinal wall is invaded, and 30% to 68% of patients have regional lymph node metastasis at the time of surgery. The metastasis pathway is generally to first transfer to the lymph nodes parallel to the colon along the marginal artery, and then along the mesenteric blood vessels that supply the diseased intestinal segment to the lymph nodes at the beginning of the vascular pedicle. This lymph node metastasis pathway, which first runs parallel to the intestinal tract and then along the mesenteric blood vessels to the central nervous system, is a characteristic of colon cancer.

The above is the spread and metastasis of colorectal cancer. Expert Tips: If you have symptoms of disease, do not delay diagnosis and go to a regular hospital for treatment in time to avoid delaying the disease and causing serious consequences. If you have other questions, please consult our online experts or call for consultation.

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