Metastasis is the spread of cancerous cells from the site of cancer to another part of the body. Unlike normal cells, these malignant cells tend to move out of the body. Almost all types of cancer can metastasize locally to neighboring tissues and organs. It can also spread to more remote parts of the body through the bloodstream or lymphatic system. The most common sites are the bones, lungs, liver and brain. Symptoms of metastasis and treatment plan may vary depending on the type of cancer. The success of treatment depends on the patient’s age, general health, type of cancer and where it metastasizes. Metastatic cancer is difficult to treat; treatments are mostly aimed at improving the quality of life of the patient.
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Metastasis is the spread of cancer to another part of the body. Cancer cells are separated from the original (primary) tumor and spread to other parts of the body in various ways to form a new tumor. This tumor is called a secondary tumor. Secondary tumors are of the same type of cancer as the primary tumor. For example, if breast cancer spreads to the lung, the cancer cells in the lung are not lung cancer cells, but breast cancer cells.
This condition is defined as “metastatic cancer” and is named according to the site where the cancer begins. For example, if lung cancer spreads to bones, it is not bone cancer, but lung cancer metastasis to bone. A metastatic tumor is generally considered to be the 4th (last) stage of cancer.
Cancer is a malignant tumor that develops by the uncontrolled division and proliferation of mutated cells in an organ or tissue. There are more than 100 types of cancer. Cancer cells are usually caused by DNA damage.
As cancerous tumors grow, they develop cancer by damaging normal tissues. Although the exact cause is unknown, the main risk factors are all kinds of chemicals including food additives, cigarettes, air-environmental pollution and many drugs.
When a new original (primary) cancer occurs in a person with cancer, it is known as a second primary cancer and is rare. Usually when a person with cancer has cancer again, it means that the first cancer has returned.
Cancer can leave the place where it started and spread to different and remote parts of the body. Normal cells produce adhesion molecules that allow them to adhere to each other. These molecules can be likened to glue. However, cancerous cells lack these adhesion molecules, which makes it easier for them to spread out.
Almost all types of cancer have the ability to metastasize, but whether they will spread to other parts of the body depends on a variety of individual factors.
The spread of cancer cells to new parts of the body occurs in 4 stages:
Going through all these steps means that the cells that initiate new tumors will no longer be exactly the same as those in the original tumor, which may make treatment difficult.
Metastatic cancer does not always have symptoms. Current symptoms are associated with the original cancer. The nature and frequency of symptoms also depends on the size and location of metastatic tumors.
Metastatic cancer cells have properties similar to those of the original cancer and are not like the cells where the cancer is located. Therefore, it can be diagnosed by medical tests. However, there is no single test to detect metastatic cancer. Different tests can reveal different things.
The tests are determined according to the original cancer type and the symptoms to be investigated. In general, imaging and blood tests such as ultrasound, computed tomography, bone scan, magnetic resonance, pet scan can be carried out, and biopsy can be performed when necessary.
Patients who have completed their cancer treatment are followed up and examined regularly. The first issue investigated during these follow-ups is the possibility of metastasis.
The metastasis treatment plan is established according to the following criteria:
In some cases, metastasis is treated mainly based on the original site of cancer. For example, if a person’s breast cancer spreads to the liver, it is still treated with drugs used for breast cancer, because the cancer cells themselves have not changed, they just live in a new place.
Doctors may switch to another treatment or try a combination of treatments when their initial treatment no longer works. Organ transplantation is not an option for metastasis.
Once the cancer has spread, it can be difficult to control. Some types of metastatic cancer can be cured by existing treatments, but most cannot be treated. However, there are treatments available for all patients with metastatic cancer. The purpose of these treatments is to slow the growth of cancer or to alleviate symptoms. In some cases, treatments may prolong the life of patient.
All types of cancer are capable of metastasizing, but some sites of metastasis are more widespread than others. The cancerous cells in the main tumor, usually located in the abdominal cavity, may metastasize more frequently to the liver, lungs or bones. The probability of metastasis according to some types of cancer is as follows:
Life expectancy may vary depending on the type of metastatic cancer, and the age and general health of the patient. Therefore, it is not possible to give a certain time. However, in general, the probability of survival from metastatic cancer is very low; it is responsible for the 90% of cancer deaths. In this case, only treatments that can comfort the patient are applied.
Clinical trials offer treatments that are not yet open to the public. A clinical trial may be the main treatment of metastases or just one of the options. Only 3 to 5% of adults with cancer participate in clinical trials. Clinical trial therapy may or may not be helpful. However, if not, it can provide researchers with information that can help future patients.
Bone metastasis occurs when cancerous cells spread to the bones from their original areas. Nearly all types of cancer can spread to bones, but some types of cancer, especially breast and prostate cancer, are more likely to spread to bones. Bone metastasis can occur in any bone, but occurs mostly in the spine, pelvis and thigh. Bone metastasis may be the first sign of your cancer or may occur years after cancer treatment.
With exceptions, cancer spreading to the bones cannot be cured. Treatments can only help reduce pain and other signs of bone metastasis. Bone metastasis can also cause paralysis and hypercalcemia (high levels of calcium in the blood).
Some cancers can start directly in the bone (bone cancer). These cancers are very different from bone metastases. Bone metastasis is much more common than original bone cancers, especially in adults.
One of the organs in which cancer cells are spread most frequently by the blood circulation is the liver. There are different treatment options depending on the number and size of liver metastases as well as the type and size of the original cancer. In many cases, liver metastasis is treated in the same manner as the original cancer (with the same drugs). Surgical removal of the tumor increases the likelihood of treatment.
The liver is one of the most susceptible organs to radiation, even a small dose of radiation can seriously impair its function and increase the risk of the patient dying of liver failure. Functions of the organ are impaired if metastasis spreads to the whole liver.
The treatment of lung metastases depends on the degree of metastases as well as the original cancer. It is often treated in the same way as the original cancer (with the same drugs). If metastasis causes fluid formation around the lung, fluid may be drawn by needle.
Depending on the number of tumors and the degree of disease in the rest of the body, treatment options may include surgery, radiation therapy, gamma knife therapy, chemotherapy and/or steroids in very specific cases.
It is important to follow the treatment plan, but coping with emotions and lifestyle challenges is also an important part of living with metastatic cancer. Recommendations for coping with this situation are:
Patients with metastatic cancer may survive for years, depending on the circumstances. Your doctor can help you have the best possible quality of life during this time. Hospitals and health centers have many resources for you and your family.
References: 1- Metastatic Cancer, 2- Lung metastases, 3- Liver metastases