Metastasis: Definition, Symptoms, Development, Routes of Propagation, Diagnosis and Treatment

It is the propagation of a pathogen from an initial or primary site to a different or secondary site within the body of the host.

Usually, it is spoken as the disseminated produced by a cancerous tumor.

Cancer occurs after the cells are genetically altered to proliferate rapidly and indefinitely. This proliferation uncontrolled by mitosis produces a heterogeneous primary tumor.

This process is known (respectively) as lymphatic or hematogenous spread. Metastasis is one of the characteristics of cancer, which distinguishes it from benign tumors.

Most cancers can metastasize, although to varying degrees. Metastasis is a key element in cancer staging systems, such as the TNM system for the classification of malignant tumors, where it represents the “M”.

In the general grouping by stages, the metastasis places a cancer in Stage IV. The chances of curative treatment are greatly reduced, or often completely eliminated, when a cancer metastasizes.

The original cancer is called the primary tumor. Cancer in another part of the body is called metastatic or secondary cancer. Metastatic cancer has the same type of cancer cells as the primary cancer.


Signs and symptoms

Some common signs of metastatic cancer include:

Lungs : cough, hemoptysis and dyspnea (difficulty breathing).

Liver : hepatomegaly (enlarged liver), nausea and jaundice .

Bones : pain in the bones, fractures when the cancer has spread to the bone.

Brain : neurological symptoms such as headaches, convulsions and vertigo .

Although advanced cancer can cause pain, it is often not the first symptom.

How does metastasis develop?

Metastases (the plural form of metastasis) develop more often when the cancer cells separate from the main tumor and enter the bloodstream or lymphatic system. These systems transport fluids throughout the body.

This means that cancer cells can travel far from the original tumor and form new tumors when they are established and grow in a different part of the body.

Metastases can also sometimes develop when cancer cells in the main tumor, usually in the abdominal cavity (belly), detach and directly “sow” other areas within the abdominal cavity.

Any type of cancer can metastasize (spread). Whether this happens depends on several factors. These include:

  • The type of cancer
  • How aggressive (rapid growth) is cancer.
  • How long have you had cancer before treatment.
  • Other factors

Some cancers, such as leukemia, lymphoma and multiple myeloma, are considered widespread when diagnosed and, therefore, are not called metastatic cancer.

Where metastasis develops

Cancer can spread to any part of the body. Most cancers tend to spread to one place more often than others. Testicular cancer usually spreads to the lungs and ovarian cancer usually spreads to the peritoneum.

Doctors can use the following terms to describe whether the cancer has spread or how much it has spread.

Regional means that the cancer has grown in the surrounding tissues or organs, or has spread to nearby lymph nodes. Distant means that the cancer is in one part of the body farther from where it started.

Doctors generally use the term metastatic cancer to describe cancer that has spread to distant organs or distant lymph nodes (called distant metastases).

The most common sites of distant metastasis are the bones, brain, liver and lungs.

Metastasis to the bones, brain, liver, lymph nodes and lungs is common. Cancer cells can also metastasize to the pleural space (the lining around the lungs) or the abdominal cavity.

This can cause an excess of fluid buildup in these areas (called malignant pleural effusions and malignant ascites). Multiple small metastases in the abdominal cavity are known as peritoneal carcinomatosis.

Less often, cancer can also spread to the skin, muscles, or other organs of the body.

Some cancers tend to spread to certain parts of the body. For example:

  • Breast cancer tends to spread to the bones, the liver, the lungs, the chest wall and the brain.
  • Lung cancer tends to spread to the brain, bones, liver and adrenal glands.
  • Prostate cancer tends to spread to the bones.
  • Cancers of the colon and rectum tend to spread to the liver and lungs.

Bone metastasis:

It is sometimes called secondary bone cancer or metastatic bone disease. Bone metastases are much more common than primary bone cancer.

The most common sites of bone metastases are the vertebrae (bones of the spine), the ribs, the pelvis (hip bone), the sternum (sternum) and the skull.

Sometimes, only one area of ​​the bone is affected. Sometimes, metastases develop in several bones at the same time.

The bone is constantly forming and decomposing. This is a normal process that keeps bones healthy and strong. Metastatic cancer can alter this process. It can affect the normal balance between new and old bones and change the structure and function of bone.

Osteoblastic metastases develop when cancer cells invade the bone and cause the formation of too many bone cells. The bone becomes very dense or sclerotic. Osteoblastic metastases often occur when prostate cancer spreads to bone.

Osteolytic metastases develop when metastatic cancer cells break down bone too much, which makes it very weak. Holes can develop in the bones as the bone is destroyed. Osteolytic metastases often occur when breast cancer spreads to bone.

Osteolytic metastases are more common than osteoblastic metastases. Osteolytic metastases and osteolytic metastases may occur together in the same area of ​​bone, such as metastatic breast cancer.

Brain metastasis:

It is sometimes called secondary brain cancer or a metastatic brain tumor. Brain metastases are much more common than primary brain cancer.

The most common site of brain metastasis is the brain, which is the largest and highest part of the brain. Less often, cancer spreads to the cerebellum and brainstem. Sometimes there is only one brain tumor, but most people develop many brain metastases.

This is called leptomeningeal metastasis or meningeal carcinomatosis. The symptoms of brain metastases vary according to the part of the brain affected. Other health conditions can cause the same symptoms as brain metastases.

The most common symptom of brain metastasis is headache. The headaches can be caused by a tumor that presses on the brain, swelling (called edema), hemorrhage or hydrocephalus.

If brain metastases are found before the primary cancer is diagnosed, the doctor may order tests to find out where the cancer started. Other tests may also be used to detect metastatic cancer in other parts of the body.

A diagnosis of advanced cancer can lead to questions about survival. There is no way to know exactly how long someone will live with brain metastases.

It depends on many factors, including the type of cancer, the number of tumors in the brain and the treatments used. Survival with brain metastases is often measured in months, but some people can survive for several years.


Hepatic metastasis:

It is sometimes called secondary liver cancer or metastatic liver disease. Most people develop many liver metastases in both lobes of the liver.

It may be necessary to diagnose liver metastases. It is done when the doctor can not determine if there are liver metastases based on imaging tests or if there is no history of cancer.

A biopsy can also be performed to verify the tumor markers that help guide the treatment. A percutaneous needle biopsy or an endoscopic biopsy may be used during laparoscopy.

If you have liver metastases, your health care team will create a treatment plan just for you. It will be based on your needs and usually includes a combination of different treatments.

Treatments can control and slow the growth of liver metastases, but most metastases do not completely disappear unless they can be removed by surgery.

The treatments can also control or prevent problems caused by liver metastases. Sometimes they are called support therapies.

Pulmonary metastasis:

It is sometimes called secondary lung cancer or metastatic lung tumors.

Cancer can spread to any part of the lungs. Sometimes there is only a single tumor in a lung. Sometimes there are many metastases in one or both lungs.

Most lung metastases develop near the edges of the lungs and in the lower lobes. Cancer can also spread to areas outside the lung, such as the pleura and mediastinum.

Pulmonary metastases may not cause any symptoms at the beginning. The symptoms of lung metastases vary according to the number of tumors and their location in the lungs. Other health conditions can cause the same symptoms as lung metastases.

Imaging tests are an important part of the diagnosis of pulmonary metastases. It is common for people to have one or more imaging tests when the doctor thinks that the cancer may have spread to the lungs. These tests include the following.

A chest x-ray is usually the first test that is done to try to find out what is causing symptoms such as cough and shortness of breath. Doctors use a chest x-ray to look for any lung tumor.

Computed tomography (CT) of the chest is a common test used to detect lung metastases.

It provides more detailed images of lung tumors than a chest x-ray, including the size and location of the tumors. It can also be used to detect cancer in nearby lymph nodes.

Positron emission tomography of the lungs or the entire body can be performed. It can be used to check whether lung tumors are cancerous or not.

Propagation routes

When the cancer cells grow and divide, they can move from where they began to other areas of the body. There are ways cancer can spread.

Direct extension, or invasion, means that the primary tumor grows in tissues or structures around it. For example, prostate cancer can grow in the bladder.

Metastasis occurs by the following routes:

Through the peritoneal cavity:

The dissemination of a malignancy towards the body cavities can occur when penetrating the surface of the peritoneal, pleural, pericardial or subarachnoid spaces. For example, ovarian tumors can spread transperitoneally to the surface of the liver.

Lymphatic extension:

Lymphatic spread allows the transport of tumor cells to regional lymph nodes near the primary tumor and, ultimately, to other parts of the body.

“Positive nodes” is a term that medical specialists would use to describe regional lymph nodes that yielded positive results of malignancy.

Lymphatic spread is the most common route of initial metastasis for carcinomas. On the contrary, it is uncommon for a sarcoma to metastasize through this route.

The lymphatic system eventually drains from the thoracic duct and the right lymphatic duct to the systemic venous system at the venous angle and into the brachiocephalic veins, and therefore these metastatic cells can also eventually be disseminated through the hematogenous pathway.

Blood propagation:

Blood or hematogenous spread means that cancer cells separate from the primary tumor, enter the bloodstream and travel to a new place in the body.

The immune system usually attacks and destroys cancer cells that travel through the lymphatic system or the bloodstream.

Channeling propagation:

Some tumors, especially carcinomas, can metastasize along anatomical canalicular spaces. These spaces include, for example, the bile ducts, the urinary system, the airways and the subarachnoid space.

The process is similar to that of transcelomic propagation. However, it is often unclear whether tumors diagnosed simultaneously from a canalicular system are a metastatic process or, in fact, independent tumors caused by the same agent (cancer of the field).

But sometimes the cancer cells survive and establish themselves in another area of ​​the body, where they form a new tumor. To survive and grow in the new location, the tumor must form its own blood supply (called angiogenesis).

Is it a metastasis of the same type of cancer that caused it?

The doctors give a metastasis of the same name as the original cancer. Therefore, a breast cancer that spreads to the liver, for example, is called “metastatic breast cancer,” not liver cancer.

This is because cancer began in breast cancer cells.

However, even though the tumors in each of these different locations represent breast cancer, doctors are learning more about how metastases may differ from the primary (original) tumor at the molecular and genetic level.

This is known as intrapaciente tumor heterogeneity.

How do doctors diagnose metastasis?

If you have already received treatment for non-metastatic cancer, you probably have a follow-up care plan. You see your doctor for regular exams and exams. Part of the reason for these follow-up tests is to look for any evidence of metastasis.

Alternatively, some people already have metastases at the time of the original diagnosis of cancer and are found during the initial staging evaluation.

Cancer may or may not cause symptoms, such as pain or shortness of breath. Sometimes these symptoms cause a doctor to perform the tests necessary to diagnose the presence of metastases.


The treatment depends on:

  • The original cancer and where it started.
  • How much cancer has spread and where it is.
  • Your age and health

Metastatic cancer is usually harder to treat than cancer that has not spread. In most cases, the goal of treatment for metastatic cancer is to prolong survival and maintain quality of life.

The treatments control and slow down the growth of the metastasis, but the metastases do not usually disappear completely. Treatments are also used to control or prevent problems caused by metastatic cancer (called supportive therapies).

The treatments offered for metastatic cancer are based on several factors, such as where the cancer started, the symptoms, the location and amount of metastases, the treatments used for the original cancer, the purpose of the treatment, your general health and your personal preferences.

Treatments that can be used for metastatic cancer include chemotherapy and other drug therapies, radiation therapy, surgery and ablation therapy. A combination of different treatments and supportive therapies is often used.

Treatment options for metastasis:

Once the cancer spreads, it can be difficult to control.

The treatment for metastasis is often different from the treatment used for the original tumor. Most commonly, doctors can try one type of chemotherapy and then switch to another when the first treatment no longer works.

Or you may have a combination of treatments, such as chemotherapy, radiation and / or even surgery to remove it.

The main treatments for metastasis include:

The treatment that affects your whole body : doctors call it “systemic” therapy. It includes chemotherapy and other medications, such as targeted therapy, hormone therapy and biological treatment.

Treatment for the area with cancer : doctors call it “local” therapy. It includes surgery, radiotherapy and some other treatments.

Does treatment cure metastatic cancer?

In some situations, metastatic cancer can be cured, but the most common is that the treatment of metastases is not curative. It is possible to live many months or even years with certain types of cancer, even after the development of a metastatic disease.

How well any treatment works depends on:

  • The type of cancer
  • How far cancer has spread and where it is.
  • How much cancer there is
  • If the cancer is growing rapidly or slowly.
  • The specific treatment

How does cancer respond to treatment?

It is important to ask your doctor about the goals of the treatment. These goals may change during your care, depending on whether the cancer responds to treatment.

It is also important to know that pain, nausea and other side effects can be controlled with the help of your health care team.

This is called palliative care and should be part of any treatment plan.

Treatment in clinical trials:

Clinical trials offer treatments that are not yet available to the public, are research studies that test new ways to prevent, find, treat or treat cancer or other diseases.

Clinical trials for metastatic cancer may be available. If you want to participate in a clinical trial, talk with your doctor or health care team to find out if you are eligible.

One trial could be the main treatment for metastasis, or just one of the options. Only 3% to 5% of adults with cancer participate in clinical trials.

The trial treatment may or may not help. But even if it does not, it provides researchers with information that could help future patients. Talk to your doctor and your health care team if you are interested in clinical trials.

Living with metastatic cancer

When you live with cancer for many months or years, doctors often treat it as a chronic (long-term) disease. As someone with another chronic disease, such as diabetes or heart failure, you need treatment.

It is important to follow your treatment plan to make it work as well as possible. He also needs support for the physical, emotional and mental challenges of living with cancer.