As we all know, easy metastasis is one of the most terrifying characteristics of tumors. Tumor cells will quietly settle on the patient’s lungs, liver, brain, and bones when the primary tumor is still very small. Therefore, some patients die from the pain of bone metastasis, and when hemoptysis or suffocation occurs due to lung metastasis, the primary tumor is still asymptomatic. Some patients thought that the tumor was happily undergoing surgery at an early stage. Soon, the metastases showed their heads one by one...

So, why do tumor cells metastasize, how do they metastasize, and where do they metastasize?

How do tumor cells appear?

Tumor cells are caused by mutations of proto-oncogenes and tumor suppressor genes caused by physical, chemical, viral and other carcinogenic factors in normal cells. For example, if you continue to be exposed to adverse external stimuli, such as smoking, radiation, drinking, and aging, the genes of normal cells will be mutated, and multiple mutations may cause cell cancer. Under normal circumstances, the body's normal mechanism and immune system will work hard to ensure the normal operation of the body and eliminate cancerous tumor cells. Therefore, the human body does not get tumors overnight.

Proto-oncogenes are usually genes that help cells grow. When a proto-oncogene is mutated (altered) or has too many copies to make it permanently opened or permanently activated, it becomes a "bad" gene. When this happens, cell growth will go out of control, leading to cancer. This bad gene is called an oncogene. Tumor suppressor genes are normal genes that delay cell division, repair DNA errors, or tell cells when to die (ie, apoptosis or programmed death). When the tumor suppressor gene does not work properly, the cell will lose control and cause cancer.

 Why do tumor cells metastasize?

Tumor cells are different from normal cells. The following characteristics make tumor cells easier to spread and metastasize. It then locally invades nearby normal tissues, even through the blood circulatory system or lymphatic system in the body, so that tumor cells can transfer to other parts of the body more quickly.

Immortal proliferation Under suitable conditions, cancer cells can proliferate indefinitely and become "immortal" immortal cells. Normal cells have a certain maximum number of divisions. For example, a human cell can only divide 50-60 times in a lifetime. However, there is no upper limit for the number of divisions of cancer cells.

The phenomenon of contact inhibition loses normal cell growth. After contact with each other, its movement and division activities will stop. Under in vitro culture conditions, the cells adhere to the wall and converge into a monolayer and then stop growing. Cancer cells are different. Their division and proliferation do not stop when cells contact each other. Cells can accumulate into somatic cell groups when cultured in vitro, so cancer cell contact has no inhibitory effect on cancer cell proliferation.

The adhesion between cells is weakened. Compared with normal tissues of the same homology, cancer cells have lower adhesion between cells, so cancer cells are easily dispersed and metastasized in the body. Fibronectin in the outer cover of normal cells is an extracellular adhesion glycoprotein that enhances the adhesion between cells and the extracellular matrix. The fibronectin of cancer cells is significantly reduced or absent, and the synthesis of cadherin is hindered, which destroys the adhesion between cells and matrix and between cells. Therefore, cancer cells have the property of easily infiltrating tissues and metastasis.

 How do tumor cells metastasize?

The process by which tumor cells spread in the body is called metastasis. When cancer cells leave the original tumor location and invade nearby normal tissues, this process has already begun. With the rapid spread of cells, they can spread to other parts of the body through different ways such as blood transplantation, lymphatic metastasis, and planting metastasis.
   
 Where do tumor cells like to metastasize?

The metastasis of tumor cells will generally be transferred to a specific destination without affecting other organs. It is also called "organ affinity". For example, breast cancer can easily metastasize to its own lymph nodes or lungs and liver, prostate cancer can metastasize to bones, spine, etc.; stomach cancer can metastasize to its own lymph nodes, causing invasion of the stomach wall, and lung cancer cells can also metastasize to the brain.

Common tumor metastases mainly include bone metastasis, liver metastasis, brain metastasis, lung metastasis, lymph node metastasis, malignant pleural effusion, malignant ascites, etc. Many tumor patients find the primary tumor because of metastatic behavior, and some of the examinations can’t Confirm the original lesion.

What are the symptoms of tumor spread?
Tumor spread may not have obvious symptoms, because the various organs of the human body have a very strong compensatory ability. Unless there is a serious metastasis, which leads to organ dysfunction, there may be obvious clinical symptoms.
Unexplained wasting
The continuous growth of cancer cells requires continuous consumption of nutrients in the body. In the long-term, patients will suffer weight loss, weight loss, loss of appetite, anemia, etc. The only ones who are severely thin are skinny. If a person is middle-aged and suddenly loses weight or loses weight, he must go to the hospital for a check.
Unexplained fever
Tumors grow very fast, and the cells in the middle will become necrotic because they cannot get nutrients. After the necrotic tissue is absorbed, it can cause low fever. Moreover, tumor cells still release some mediators of inflammation, which can also cause fever, and the body temperature is generally lower than 38 degrees Celsius. If you have a low-grade fever, no clear cause, no cold, no signs of infection such as pneumonia, you must go to the hospital.
Painless lump
There are a lot of superficial lymph nodes in our body. If you feel one or more on the clavicle, armpits, groin, or neck, there are hard masses that are not painful and have poor mobility. Be wary of lymph node metastasis or lymphoma caused by cancer.
 
Special symptoms
Tumor metastasis to different organs can cause different symptoms. For example, cancer cells metastasize to the brain, which can cause headache, dizziness, nausea, vomiting, sensory and movement disorders, etc.; cancer cells metastasize to the spine and bones, which can cause metastasis. Severe pain, pathological fractures, compression of nerves, motor and sensory disturbances; cancer metastases to the liver, abdominal pain, liver dysfunction, jaundice, elevated transaminase, etc.

How to prevent and treat tumor metastasis?

After the tumor has metastasized to the whole body, it belongs to stage IV tumor, which is what we call advanced tumor. In most cases, the treatment effect of advanced tumors is not very good, and it is difficult to cure, so the prevention of tumor metastasis is the key. The following measures are adopted to reduce the tumor metastasis rate as much as possible and extend the life of patients.
Regular review after operation
After standard treatments such as surgery, radiotherapy and chemotherapy, it is not going to be done once and for all, because tumor cells may recur and metastasize. Therefore, regular review is required, especially in the 5 years after surgery. The first 5 years are the peak period of recurrence and metastasis. If metastasis is detected early, it can be treated actively to achieve good results.
healthy lifestyle
Regardless of whether you have cancer or not, you need to maintain a healthy lifestyle, strengthen your physical fitness, and reduce the rate of cancer recurrence. A healthy lifestyle includes: work and rest, moderate exercise, regular meals, quit smoking and alcohol, avoid overeating, light low-fat diet, high-quality protein diet, not staying up late, not overwork, early to bed and early to wake up. Only by doing a healthy lifestyle can we improve our immunity and minimize the cancer recurrence rate.
Optimistic
A good attitude and mood are also crucial to the treatment of cancer. Many studies have shown that maintaining a relatively optimistic attitude after cancer surgery can help fight cancer, improve one's own immunity, reduce recurrence rate, and improve survival rate.
Comprehensive Treatment
What if the tumor has metastasized? Don't panic, the current comprehensive treatment of tumors is no longer what it used to be. If it is a single organ metastasis, there is still a chance for surgery, surgical resection is recommended. If the tumor is widely metastasized and there is no opportunity for surgery, chemotherapy, radiotherapy, endocrine therapy, targeted therapy and immunotherapy can be done according to the patient’s physical condition and tumor condition. It is hopeful that the tumor will survive for a long time, especially the recent hot immunotherapy. Some patients with advanced stage, through immunotherapy, all the tumor cells were magically killed, and the cure effect was obtained.

Let us sincerely hope that with the joint efforts of mankind, we can successfully stop tumor metastasis and give patients hope of cure.