September 14, 2023
1. What is blood transfer?
After the malignant tumor cells invade the blood vessels, they can follow the blood flow to the distant organs, continue to grow and form metastatic tumors. Because the vein wall is thin and the intravascular pressure is low, most of the tumor cells enter the blood through the vein, and a few can also enter the blood indirectly through the lymphatic-thoracic duct-vein pathway. The pathway of blood metastasis (hematogene-ous metastasis) is the same as that of emboli, that is, the tumor cells entering the systemic circulation vein pass through the right heart to the lung, and form metastases in the lungs, such as lung metastasis of choriocarcinoma and osteosarcoma. Liver metastasis occurs first when tumor cells invade the portal vein system, such as liver metastasis of stomach and intestinal cancer. The tumor cells or lung metastases entering the pulmonary vein enter the pulmonary vein through the pulmonary capillaries, and can reach the organs of the whole body through the left heart with the blood flow of the aorta, and often metastasize to the brain, bone, kidney and adrenal gland. Tumor cells invading the veins of the anastomotic branches of the vertebral venous plexus can cause spinal and brain metastasis, such as spinal metastasis of prostate cancer.
two。. What is a cancerous navel?
Malignant tumors can involve many organs through blood metastasis, but the most commonly involved organs are lungs, followed by liver and bone. Therefore, the imaging examination of lung, liver and bone must be performed in patients with malignant tumor to determine the occurrence of blood metastasis in order to determine the clinical stage and treatment plan. Morphologically, metastases are characterized by clear boundaries, often multiple, scattered and close to the surface of organs. The metastatic tumor on the surface of the organ, due to bleeding and necrosis in the center of the tumor nodule, can form the so-called "cancer navel".
Not all malignant tumor cells that enter the blood vessels can migrate to other organs to form metastatic foci. Most of the single tumor cells were destroyed by natural killer cells (NKcell). However, tumor cells agglutinated with platelets form tumor cell thrombus that is not easy to destroy, which can adhere to vascular endothelial cells and pass through vascular endothelium and basement membrane to form new metastatic foci.
