Three metastatic pathways of colon cancer

Many cancers will metastasize when they develop to a certain stage, and this is also true for colon cancer. There are three main ways for it to metastasize.

1. Distant metastasis

The main distant metastasis of colon cancer is the liver. About 50% of patients will have liver metastasis before or after surgery. Data show that about 30% of patients have occult liver metastasis that cannot be detected by B-ultrasound or CT before surgery. Colon cancer liver metastasis resection is safe and is currently a treatment method that may improve the long-term survival rate of patients with metastasis. However, only a small number (10%-20%) are suitable for surgical resection, and 70% of them relapse after surgery.

2. Lymphatic metastasis

Lymph node metastasis of colon cancer generally spreads from near to far in the following order, but there is also non-sequential cross-metastasis.

Colonic lymph nodes are located in the fat villus of the intestinal wall.

Paracolic lymph nodes are located in the mesentery adjacent to the colon wall.

Mesenteric vascular lymph nodes are located next to the blood vessels in the middle of the colon mesentery and are also called the intermediate lymph node group.

Mesentery root lymph nodes are located at the root of the colon mesentery. The chance of lymphatic metastasis increases when the tumor invades the intestinal wall muscle layer. If the subserosal lymphatic vessels are invaded, the chance of lymphatic metastasis is even greater.

3. Hematogenous metastasis

Generally, cancer cells or cancer emboli first reach the liver along the portal vein system, and then reach other tissues and organs such as the lungs, brain, and bones. Hematogenous metastasis usually occurs when the tumor invades the capillaries and small veins, but it can also be caused by pressing the tumor during a physical examination, squeezing the tumor during surgery, or even strong peristalsis during obstruction, which can cause cancer cells to enter the bloodstream.