Why are tumor metastases located in important organs? Let's explore this from the perspective of traditional Chinese medicine.

Earlier in 2021, the World Health Organization's International Agency for Research on Cancer (IARC) released the "2020 Global Cancer Report". In 2020, there were 19.29 million cases of cancer diagnosed worldwide and 9.96 million deaths; 4.57 million cases were diagnosed in China and 3 million deaths. The incidence and mortality rates of cancer are rising both in the world and in China. Early cancer is easy to cure, but when cancer metastasizes, its treatment effect will be greatly reduced, because cancer metastasis often metastasizes to some important organs, which makes treatment very difficult. Why do cancer metastases mostly to important organs? Let's discuss it.

Understanding of tumors in China and the West Tumor is a general term. Tumor refers to a new growth formed by the proliferation of local tissue cells under the action of various tumorigenic factors. Because this new growth is mostly a space-occupying mass protrusion, it is also called a growth. Western medicine has not yet given a reasonable and detailed explanation for the complex formation of tumors. In other words, Western medicine currently believes that the cause of tumors is unknown.

Chinese medicine generally believes that tumors are severe cold stagnation diseases, and their development actually consists of four steps: Yang deficiency, Yin excess, cold stagnation, and tumors. Specifically, the process is as follows: If the human body lacks Yang for a long time, the body will be in a state of imbalance between Yin and Yang, disharmony between Qi and blood, and disorder of internal organs. At the same time, if Yang is insufficient, the defensive Qi will not be solid, and exogenous evil will take the opportunity to invade the human body, further destroying the normal physiological functions of the body and consuming basic substances such as Qi, blood, essence, and body fluids. When Yang is deficient, Yin is excessive. Because "Yang turns into Qi, and Yin forms", it will cause pathological changes such as Qi stagnation, blood stasis, phlegm coagulation, poison accumulation, and dampness stagnation, and then produce various pathological products. Over time, these pathological products will collude with each other to form a tangible tumor - a tumor.

Tumor metastasis and pathological changes Tumors are divided into benign tumors and malignant tumors. Intuitively speaking, tumors that can metastasize are malignant, and tumors that cannot metastasize are benign. Malignant tumors can be divided into two categories from a histological perspective: one is caused by the malignant transformation of epithelial cells, which is called cancer. Cancer cells will grow and metastasize without limit, destroy the body's immune ability, tissue function and tracheal function, shorten the patient's life span, and even cause death; the other is caused by the malignant transformation of mesenchymal tissue, which is called sarcoma. Generally speaking, "cancer" refers to all malignant tumors.

In summary, there are four main ways for cancer cells to transfer from the primary site to other sites: ① Direct metastasis, which spreads directly from the primary site to adjacent sites. ② Lymphatic metastasis, in which cancer cells from the primary site transfer to lymph nodes at all levels from near to far through the lymphatic system. ③ Hematogenous metastasis, in which cancer cells from the primary site "take a ride" on the blood flow and reach organs such as the lungs, liver, bones, and brain. ④ Seeding and transplantation, in which tumor cells fall off and arrive at another site, where they "take root and sprout", such as cancer cells from internal organs being implanted on the peritoneum or pleura.

Although tumors have certain ways of metastasis and can metastasize to many parts of the human body, the most common ones are metastases to specific important parts such as bones, lungs, brain, liver, etc. This not only makes treatment more difficult, but also greatly reduces the survival rate of patients. So why do tumors prefer to metastasize to these important parts of the body?

Why are tumor metastases located in important organs? The most widely accepted theory about cancer metastasis is the "seed-soil theory", which compares cancer cells to "seeds" and the destination of cancer metastasis to "soil". Tumor metastasis is the result of the growth and development of special tumor cells (seeds) in their appropriate tissue microenvironment (soil). However, people currently cannot fully reveal why cancer cells are prone to metastasize to certain specific parts using Western medical theories. They have only summarized the parts to which different types of cancer are prone to metastasize in clinical practice.

Traditional Chinese medicine believes that the target organ of tumor metastasis must be a microenvironment suitable for the growth of tumor cells. Tumor cells have the physiological characteristics of "yin in body" and "yang in function". The specificity of target organs of tumor metastasis is closely related to the theory of meridians and viscera.

There are many meridians connected to the lungs, which makes all organs closely connected to the lungs. According to the meridians, eight of the twelve meridians and two collaterals go up to the lungs, go up to the lungs, penetrate the diaphragm and connect to the lungs, belong to the lungs, and connect the heart and lungs, which are more detailed descriptions of the lungs connecting to all meridians. The lungs have abundant meridians, so organ tumors are easy to metastasize to the lungs.

The liver can be directly connected to the gallbladder, stomach, lungs, heart, pericardium and other internal organs through the meridians. Although there are not many meridians connecting the liver, the liver is responsible for storing blood. When a person moves, blood flows to the meridians, and when a person is still, blood returns to the liver. The presence of slow-moving blood in the liver is easy to cause metastatic lesions.

The head is the meeting point of all yang, and there is a meridian in the body that runs from the top of the head to the brain. Cancer can spread to the head along the meridian. Due to the directionality of the meridian, intracranial tumors rarely metastasize to the extracranial part, while extracranial tumors often metastasize to the intracranial part.

Malignant tumors are prone to bone metastasis, and the kidneys are responsible for bone and marrow production. However, long-term illness will cause the kidney qi to become weak and unable to nourish the bones and produce marrow. The cancerous toxins travel along the meridians and blood to reach the bones and form metastatic foci.

Finally, the early detection and early treatment of malignant tumors can still achieve satisfactory results for patients. The increase in cure rate is due to the improvement of early diagnosis and treatment technology and the enhancement of people's awareness of health examinations, but medical technology has not made substantial progress in the treatment of patients with advanced tumors. Preventing tumor recurrence and metastasis is the key and difficulty in the treatment of hydrazine tumors. It can be seen that there is still a long way to go in the study of the understanding of the metastasis mechanism of malignant tumors.