Metastases develop when cancer cells break away from the original tumor and enter the bloodstream or lymphatic system. They then travel to distant locations where they grow into new tumors.
Most metastatic tumors grow by forming blood vessels around themselves to nourish themselves, but some can also spread without establishing new blood vessels.
When cancer cells spread from their original location in the body to bone, it is called metastasis. Nearly all types of cancer can spread to the bones, but breast and prostate cancer are especially likely to do so. Bone metastases can happen in any bone in the body, but they occur most often in the pelvis, femur (hip), sternum (chest), ribs and skull. They may cause no symptoms and are sometimes discovered only by a biopsy. If they are painful, doctors can treat them with drugs that strengthen the bones and relieve pain.
The most common symptom is bone pain. It can be dull and boring, or it can be severe and radiate from the bone to other areas of the body. It can be more intense with movement or when you change position. Occasionally, it can cause spinal cord compression that causes problems with walking or even breathing.
If the spine is affected, your doctor will watch it very closely. Spinal metastases that grow quickly and cause pressure on the spinal cord can cause paralysis in the legs, loss of control over when you urinate or defecate, confusion and possibly a coma. If you have this problem, you may need to be hospitalized.
Your doctor can find out if you have bone metastases through tests like x-rays, bone scans and MRIs. X-rays and MRIs can also see osteolytic lesions that look like holes in the bone. A PET (positron emission tomography) scan is a nuclear scanning technique that uses radio waves and strong magnets instead of X-rays. It can help detect the presence of certain substances in your body, such as sugar and phosphates.
The most commonly used drug to prevent bone problems in people with metastatic breast cancer is the bisphosphonate drug pamidronate (Aredia) or zoledronic acid (Zometa). This is given by injection into a vein or by mouth. It is usually given once a month at first, but it can be treated less often as you get better. It can also be given in combination with a chemotherapy drug that kills cancer cells.
Cancer cells that spread from their original location in the body to the brain form a mass or tumor known as a brain metastasis. They can develop quickly or appear many years after the primary cancer. Melanoma has a special tendency to metastasize to the brain, but other systemic malignancies such as lung cancer, breast cancer, colon and renal cell (kidney) cancer also frequently spread to the brain.
When a person is diagnosed with brain metastases, it can be extremely difficult to come to terms with the news and to cope with challenging symptoms and side effects that arise. It is important for everyone involved in the treatment of this challenging complication to work together to find treatments that can minimize the pain and maximize functional outcomes.
Brain metastases can often be treated with a combination of symptomatic and systematic approaches. Surgical resection is standard of care for limited brain metastases in patients with good performance status who have surgically accessible lesions. The remainder of patients are treated with whole-brain radiation therapy or stereotactic radiosurgery, depending on individual risk factors. These treatments are more effective than they were in the past, and recent improvements in MRI imaging and radiation technology have significantly improved outcomes.
These procedures are non-invasive and do not require general anesthesia. They involve using a scanner to scan the brain and deliver a dose of radiation in a very precise way to each site. This can be done with a conventional linear accelerator or with specialized machines such as the Gamma Knife, Cyberknife and XKnife. Several brain metastases can be treated in one session.
Until recently, people with brain metastases from melanoma had a poor prognosis. However, with advances in radiation and systemic therapies, melanoma brain metastases have improved. It is important to have a multidisciplinary team in place including a neurosurgeon, radiologist and radiation oncologist to formulate the best treatment plan for each patient. Discuss your options with these members of your treatment team and talk openly about your goals and priorities. They might include living as long as possible, maintaining a specific quality of life or avoiding certain side effects that would be detrimental to your health.
As cancer cells break away from a primary tumor and travel through the blood or lymph system, they may end up in nearby lymph nodes. Normally, the lymph nodes act as filters to keep foreign substances, such as viruses and bacteria, from spreading throughout the body. But, if a cancer cell gets through, it can start growing in a new area and become a full-blown tumor. This is called metastasis.
Lymph nodes are bean-shaped organs that help filter viruses, bacteria and cancer cells out of the body. They are located in many parts of the body, including the neck, armpit, chest and abdomen (belly). Lymph nodes are part of the immune system, which aims to fight infection by attacking and destroying germs that enter the body through the lymph fluid.
When cancer cells spread to a lymph node, it is called a nodal metastasis. If a nodal metastasis is found, it is important information when staging a patient’s cancer using the TNM system. The TNM system is based on how much the tumor has grown, whether it has spread to nearby lymph nodes and, if it has, whether the lymph nodes have metastasized.
Researchers have been trying to develop a system that can accurately predict which patients might have node-positive lymph nodes before surgical resection. They have analyzed factors such as the size of the primary tumor, the site of the lymph node metastasis and the histology of the node. However, the prediction systems are not yet reliable enough to allow for precise surgical planning.
A study published May 6 in the journal Cell suggests that this is because tumor cells in lymph nodes encourage the immune system to protect the initial tumor rather than attack it, and this can give the cancer cells a pass to spread to other parts of the body. The research was funded by NCI’s Cancer Systems Biology Consortium.
In addition, studies of gamma-kappab ligands and their receptors suggest that certain chemokines are involved in the process of lymph node metastasis. In particular, the chemokines CXCR3 and CXCR4 seem to be critical in the recruitment of melanoma cells to lymph nodes.
As cancer cells break away from the original tumor, they most often travel through the bloodstream or lymphatic system to distant parts of the body. Once there, they settle and grow into new tumors that are called metastases. Metastases most commonly develop in the lungs, liver, and bones. They can also spread to the lining of the lungs (the pleura), causing malignant pleural effusion, and to the peritoneum, causing malignant ascites.
The process of metastasis is very complex and requires many steps for cancer cells to successfully colonize a distant site. This process is aided by the growth of a network of blood vessels, an event called tumor angiogenesis. In addition, the cancer cells must survive in their new environment and avoid being killed by the host’s natural immune system.
Metastases are more dangerous than tumors that stay confined to the organ in which they originated. In fact, the majority of deaths associated with cancer are due to metastasis of the original tumor to other sites in the body.
When cancer spreads to the lungs, it is most commonly found in the pulmonary interstitial lung (PIL), which is located between the alveoli of the lungs. It is also found in the pleural effusion and peritoneal sac surrounding the lungs, though less frequently. Cancer that spreads to the liver is more likely to be found in the hepatobiliary junction, which connects the liver to the portal vein. Cancer that spreads to the bone is most common in the trabecular bones of the pelvis and femurs, although it can also be found in other bones.
The most important factor in the development of metastases is the genetic mutations that lead to uncontrolled cell growth. These mutations may occur at any point in the life cycle and are responsible for many different types of cancer. As more is understood about the molecular events that promote metastasis, it is becoming increasingly possible to inhibit this deadly process. Current research into the inhibition of metastasis is focusing on understanding which steps in the process are most amenable to treatment.
Cancer cells can break away from a primary tumor and spread to other parts of the body, forming new tumors. These are called metastases.
Symptoms vary depending on the location of the new tumor. For example, cancer that spreads to the bones may cause pain, and lung cancer may cause a cough or fluid around the lungs.
Pain is the first symptom that most lung cancer patients notice. This is most often felt at the site of a bone metastasis, but it may also be felt in areas surrounding the pain. The pain can be sharp or dull and may be worse at night. It can also cause a feeling of pressure on the spine or limbs. Bone metastasis can also cause bone fractures, but this is not common and is usually the result of a fall or injury rather than an ongoing problem.
Most people with metastatic bone cancer do not experience other symptoms, except for the pain. But in rare cases, cancer that spreads to the bones can cause other problems, like broken bones or spinal cord compression. In this case, the cancer can be treated with surgery and radiation.
Bone metastasis can also damage the bone marrow, which reduces blood cell production. This can lead to anemia, which can make you feel tired and weak. The cancer may also affect the white blood cells, which can lead to infections and fevers. The treatment for bone metastasis is similar to that for lung cancer.
It is important to report any pain you are experiencing to your health care providers. They can help you manage it better than if they don’t know about it. They will need to monitor you closely to make sure that the pain is not caused by other health problems.
Many cancer treatments can lower your appetite. This can be a side effect of the treatment itself or it may be caused by other health problems that you have. If you have a low appetite that lasts more than a few days, tell your doctor or specialist nurse. This symptom might be a sign that the cancer has spread to your lungs.
It is also important to tell your doctor if you are not feeling hungry even when you have food available. If you lose too much weight or you are very dehydrated, this can affect your quality of life and how well you respond to treatment.
Some people with metastatic cancer experience loss of appetite (also known as anorexia). This might be caused by the cancer or by its treatment. It might also be a side effect of medications used to treat other illnesses, including depression and some antibiotics.
Bone metastases are the most common symptom of cancer spreading to the bones. The pain from bone metastases can come and go, or it might be constant. Sometimes, the pain may be in just one area of the body, such as in the spine, ribs or pelvis. Other times, it can happen in several areas of the body at the same time.
Other symptoms of bone metastases include a broken bone, weakness or changes in the way the bones feel. Liver metastases can cause fatigue, but they can also lead to liver damage and other health problems. Other symptoms of liver metastases can be a change in how the skin looks, blood in the stool or yellowing of the eyes and skin. Some patients may not have any symptoms at all.
Cancer cells can break apart from the original tumor and enter the bloodstream or lymphatic system, which carry fluids around the body. They can then travel to distant organs, where they grow and form new tumors, called metastases. Metastases most often develop in the liver, lungs, and bones, but they can also form in other places. Cancer that spreads to a nearby tissue or organ is called a regional metastasis, while cancer that spreads to a distant organ is called a distant metastasis. Most metastatic cancers cannot be cured, but ongoing treatments can slow their growth and help control symptoms.
The symptoms of metastasis vary depending on the area of the body where cancer has spread. For example, cancer that spreads to the bone may cause pain and an increased risk of fractures. Cancer that spreads to the brain can cause headache, seizures and changes in how a person thinks and behaves. It can also cause confusion and memory problems. Cancer that spreads to the lungs can cause chest pain, cough and shortness of breath. Cancer that spreads to the liver can cause jaundice (high levels of bilirubin in the blood can make the skin and whites of the eyes yellow), loss of appetite, nausea and bloating.
If you are experiencing these symptoms, talk to your doctor. He or she can order imaging tests, such as an MRI (magnetic resonance image) or a PET scan. These tests can help identify the location of a metastasis, as well as other health conditions. If the metastasis is in a bone, your doctor can also inject a dye that will highlight it on an X-ray or CT scan.
Some cancers spread from the original site to distant sites in the body by way of the bloodstream or lymph system. The new locations are called metastases. When metastatic tumors occur, it is considered advanced cancer because it has spread beyond the original site.
The most common symptom of cancer metastases is nausea, which can be caused by many different factors. It may be a side effect of chemotherapy or other cancer treatment, it can be caused by the disease itself or it can be triggered by specific smells or foods.
Nausea is feeling queasy, sick to your stomach or like you might throw up. It can also be a sign of certain types of cancer, but most often it is associated with the chemotherapy or radiation therapy being received by someone with cancer. People who receive these treatments can often take medicine to prevent or control nausea and vomiting. These medicines are called anti-nausea or emetic drugs. Some are quick-acting and are given just before each treatment; others last longer and are usually only needed when the person is getting chemotherapy or other cancer treatment.
Some cancers that begin in the breast, melanoma or lung can spread to the liver and become a liver metastasis. Liver metastases can lead to pain, jaundice, fluid around the lungs (malignant pleural effusion) and loss of appetite.
Brain metastases are a result of the cancer cells breaking away from the original location and traveling through the bloodstream or lymph system to the brain. Symptoms can include headache, changes in vision or speech and difficulty walking. If you have these symptoms, talk to your doctor right away. He or she will want to perform a diagnostic test to determine the cause of your symptoms and to help you manage them.
Fatigue is one of the most common side effects of cancer and its treatment. It’s a feeling of overwhelming tiredness and exhaustion that doesn’t go away with rest or sleep. This can be a long-term problem that affects your quality of life. It may last a few weeks (acute) or months or years (chronic).
It can be difficult to describe how you’re feeling to others, as it can look different from person to person. Some people describe it as a general feeling of weakness, whereas others may feel it in specific parts of the body. It can also be worse at certain times of the day or during specific activities. For example, some people find that they feel more tired when having chemotherapy, or before and after surgery.
There are many things that can cause cancer-related fatigue, including pain, insomnia, stress and some medicines. However, the most important factor is probably the type of cancer and the treatment you receive.
Cancer cells can break away from the original tumor and travel to other parts of the body, where they develop secondary tumours, known as metastases. If the cancer spreads to the brain, it can cause symptoms such as dizziness, blurred vision and weakness. Bone metastases can cause pain in the area where the bone is located, and if cancer has spread to the lungs, patients can experience breathing problems, coughing up blood and fluid around the lungs.
Metastases are cancer cells that have spread from the organ they started in to distant parts of the body. They can form masses in the lungs or bones.
Local surgery or radiation and systemic approaches such as chemotherapy, targeted therapy, and immunotherapy are the mainstays of metastases treatment.
At MSK, researchers are working to better understand the biology of metastasis and how to disrupt its cryptic phase and dormancy.
When cancer cells break away from where they first formed and enter the bloodstream or lymph vessels, they can travel to other parts of the body. They then start growing and forming new tumors. This process is called metastasis. It can happen anywhere in the body, but it often spreads to the bones, liver, and lungs.
The process of how these maverick cells spread to other parts of the body is complex and still largely mysterious. Cancers grow out of control and spread to other areas because they have mutations in their genes that cause them to behave differently than normal cells. Cancers can also spread because they grow so quickly that they outpace the normal cells surrounding them.
Once these maverick cells leave their original home in the primary tumor, they must survive the strange and stressful conditions of the blood vessels and tissues that carry them. They must survive the intense physical forces of the circulatory system, including the dizzying 3 to 4 mph speed at which the blood moves. They must breach the walls of blood vessels and lymph nodes, and they must survive the strange new environment of these organs and tissues.
Survivors of metastatic cancer describe their symptoms as a combination of the effects of the type of cancer and the area where it spreads in the body. For example, patients with cancer that spreads to the bones may experience pain and a higher risk of fractures. Those with cancer that spreads to the liver may experience jaundice (a yellowing of the skin and eyes).
While cancer cells are spreading, they must secrete proteins to help them cling to other cells or break through their own cell walls. These secreted proteins are known as chemokines, and they attract other cancer cells to the site where they are growing. They also bind to certain proteins in the bloodstream, which transports cancer cells throughout the body.
To make this journey, a cancer cell must also change its shape and surface to avoid being tagged as a foreign invader by the immune system. This is a big change for a maverick cell, and it takes courage to face the unknown. To do so, the cell secretes a large number of molecules that resemble peptides found in the cell wall of other cells.
Cancer cells can spread from their original site to other parts of the body. This process is called metastasis. It can happen in different ways, but it usually happens after the original tumor grows too large. The cancer cells then break away from the original tumor and move through the blood or lymph system to other places in the body. Eventually, they settle and grow in these new areas, forming new tumors. The most common places that cancer spreads to are the bones, liver, and lungs.
The lungs are 2 sponge-like organs that are located in the chest. They bring oxygen in and get rid of carbon dioxide, a waste product. If cancer cells from another part of the body (like the breast or brain) spread to the lungs, it is called metastatic cancer. The lungs are also known as secondary cancer in the lungs.
When cancer cells spread to the lungs, they often develop in the bronchial tubes that carry air to and from the lungs. They may also spread to the pleura, which is the lining around the lungs and other organs. Metastatic cancer in the lungs is sometimes referred to as stage 4 non-small cell lung cancer (NSCLC).
Typically, cancer cells that spread to the lungs form a single or multiple tumors in the bronchial tubes or pleura. These tumors can be either benign or malignant. They can also resemble adenocarcinoma or squamous cell carcinoma, the 2 types of cancer that start in the lungs.
Metastasis can occur in any area of the lungs, but they are most likely to spread to the lung parenchyma or the peribronchial glands. This is because the peribronchial glands are close to where the lungs meet the chest wall. Besides, the lung parenchyma is located in the lobes of the lungs.
When a cancer spreads to the lungs, it is usually considered advanced cancer because the primary tumor has grown too large and is now hard to treat. Symptoms of metastatic cancer in the lungs include coughing up blood, chest pain, or breathing problems. Often, these symptoms are caused by other health conditions, so it is important to talk to your doctor if you experience them.
When cancer cells break away from the primary tumor in a person’s body, they can spread to other parts of the body including the bones. This process is called metastasis. Bones are the third most common site for cancer metastasis, after the lungs and liver. It is important to understand that cancer that has spread to the bone is still considered to be breast cancer, not bone cancer. Bone metastasis is not a separate disease and is not treated differently than other types of metastatic cancer.
Bone metastasis can happen in any bone in the body, but it is more common in the limbs and skull. Cancers that commonly metastasize to the bones include melanoma, kidney cancer, breast cancer, and prostate cancer. Bone metastasis is also a side effect of certain medications, such as chemotherapy drugs.
Some people with bone metastasis may not have any symptoms. For those who do, the symptoms depend on the location of the tumor. For example, if the tumor is in the spine, it can cause back pain and/or spinal cord compression. The symptoms of bone metastasis in the limbs can include numbness or weakness in the legs and arms.
If a person is having symptoms, it is important to see a physician. A physician can evaluate the symptoms and decide on a treatment plan.
A physician will use imaging tests to find the site of the bone metastasis. These include X-rays, magnetic resonance imaging (MRI), and/or positron emission tomography (PET). A PET scan uses a small amount of a dye that “lights up” areas with abnormalities.
Some treatments for bone metastasis include surgery, radiation therapy, and/or bisphosphonate drugs. Bisphosphonates are medicines that help bones hold on to calcium and make them stronger. They also lower high levels of calcium in the blood (hypercalcemia) and prevent bone fractures. Radiation therapy uses high-energy rays to kill cancer cells and relieve pain. Surgery can remove the tumor, if possible. It can also relieve pressure from a tumor on the brain (mass effect). In addition, it may be beneficial to participate in a clinical trial that offers new therapies for bone metastasis.
When cancer cells start to grow and multiply, they can break away from their original site. They can then travel through the bloodstream and lymph system to settle in other areas of the body, where they grow into new tumors. This process is called metastasis. Cancer cells can spread to any part of the body, including the skin.
If a cancer cell spreads to the skin, it can cause an abnormal lump or patch of skin. Most skin cancers can be cured, but some types of skin cancer may spread to other parts of the body, including vital organs. This is why it is important to see your doctor if you notice any unusual growths on your skin.
A diagnosis of metastatic cancer can be frightening. However, there are treatments available that can help ease your symptoms and prolong your life. It is also important to seek support from family and friends during this time. If possible, consider joining a support group with other people who are dealing with the same issues.
The most common type of skin cancer is basal cell carcinoma and squamous cell carcinoma. They begin in the outermost layer of the skin, and they are usually cured if caught early. Melanoma, the third most common type of skin cancer, begins in the melanocytes, and it is usually fatal if not treated early.
Most cancers that spread to the skin do so through the bloodstream or lymphatic system. However, they can also spread directly from the primary tumor to the skin. This is called hematogenous metastasis. Hematogenous metastasis is more common in patients with advanced-stage cancer.
Hematogenous metastasis is thought to be facilitated by the presence of circulating tumor cells (CTCs). These CTCs are released from the primary cancer and circulate in the bloodstream, where they can settle in other tissues and form a secondary tumor. Other factors that contribute to hematogenous metastasis include wound healing, inflammation, and adipose tissue.
Cancer cells that spread to areas of the body far away from where they began are called metastatic tumors. They usually travel through the bloodstream or lymph system.
The most common places for metastases to develop are the lungs, liver and bones. But it can happen anywhere in the body.
When cancer cells break away from their original tumor mass and enter the bloodstream or lymphatic system, they can spread to distant parts of the body, a process known as metastasis. When this happens, the cancer is said to have “metastasized.”
Most frequently, cancer cells metastasize to organs such as the lungs and liver. These organs are situated directly downstream from the site of origin (or primary tumor) of most solid cancers, and they serve as “superhighways” that allow circulating cancer cells to settle in a distant location and grow into new tumors.
The lungs and liver are particularly well-suited for this purpose because they are the first tissues that circulating cancer cells encounter during their dissemination from the primary tumor. These cancer cells may also cling to the surface of the kidneys or bladder, where they can then settle in and grow in the tissue that covers these structures.
Cancer cells that enter the bloodstream must successfully pass through an obstacle known as the basal lamina, a layer of tissue that lines the interior of the blood vessels. To do this, they secrete a series of proteins that act as molecular scissors to cut through the protein barriers that inhibit their migration. They then float through the bloodstream until they reach a site where they can set up a new tumor and begin to grow.
In order to do this, they must first create a network of new blood vessels in the area where they are establishing a new tumor. This is a process known as tumor angiogenesis, and it requires the help of other cell types, such as endothelial cells. Cancer cells secrete a protein known as vascular endothelial growth factor (VEGF), which stimulates the activity of a cell type called Src kinase. This causes proteins called cadherins to disengage from each other. In the presence of VEGF, these proteins no longer serve to keep endothelial cells from binding with each other, allowing the migrating cancer cells to enter the tissue surrounding the blood vessel.
If a physician suspects that the patient has metastatic cancer, he or she may run tests such as an MRI or PET scan to identify the location of these sites of disease. An MRI uses magnets and radio waves to take pictures of the internal structure of the body, while a PET scan measures changes in cellular metabolism and uses a dye containing a radioactive tracer to “light up” troublesome areas.
Cancer cells can also spread to lymph nodes, which are located throughout your body. Lymph node metastases (LNMs) are a common complication of cancer from many types of tumors, including colorectal cancer. They are usually diagnosed through a physical examination, radiologic imaging and a biopsy. LNMs can be treated with surgery, chemotherapy or radiation.
A tumor cell must be able to do all three of these things well in order to successfully metastasize: it needs to break out of the original tumor, invade its host tissue and then enter the bloodstream. It is this third stage that is the hardest to control, and it is in the bloodstream where most of the metastatic growth occurs.
To understand what conditions cause a tumor to spread, scientists have developed models to simulate different metastatic scenarios. These models include:
One popular model is the “Seed and Soil Hypothesis.” This assumes that cancer cells are most likely to meet other similar cells and grow together. This leads to the formation of secondary tumors at sites in the body where the primary tumor first metastasized. For example, colon cancer frequently metastasizes to the liver. This is because the colon was likely the first organ where the cancer cells encountered a capillary bed.
Another model focuses on the role of the microenvironment in metastasis. The microenvironment is the environment that surrounds and supports a growing tumor, and it plays an important role in the development of metastasis. A key hypothesis in this model is that the microenvironment creates favorable conditions for the growth of metastases, and that successful metastatic cells are those that can survive in all phases of the process.
Scientists have also investigated the genetic differences in metastatic cancer. They have found that different mutations are present in individual metastases and that these changes occur over time. They have also discovered that some metastases can be linked to a single clone of the original tumor.
Some metastatic cancers, such as melanoma, are more adept at spreading to lymph nodes than other cancers. However, this doesn’t mean that it cannot spread to other places. In fact, metastatic melanoma has been found in the lungs and bones of patients with no known point of origin.
Bone metastases occur when cancer cells break away from their original site, travel throughout the body, and invade a bone. Bone is one of the most common sites for cancer metastasis, along with the lungs and liver. Metastasis that spreads to the bones is called bone metastasis or bone lesions.
Cancer that has spread to the bone is called late-stage or advanced cancer. It can happen in any bone, but it is most common in the spine (vertebrae), pelvis, upper leg bone (femur), humerus, ribs, and skull. Cancer that spreads to the bone is also referred to as osteosarcoma, metastatic carcinoma, and malignant sarcoma.
Normally, the bones are kept strong by 2 kinds of cells: bone forming (osteoblasts) and bone breaking down (osteoclasts). When cancer metastasizes to the bone, it affects these 2 processes. The tumor may cause the bone to break down faster than it can form, which can lead to pain and a weakened bone that is more likely to fracture or break. The tumor may also release growth factors that cause the bone to grow and the tumor to spread within the bone.
The weakened bones may cause bone pain, which is often the first symptom of metastasis to the bone. This pain usually comes and goes at first, gets worse at night, and is relieved by movement. In time, the pain can become constant. The weakened bones can also lead to serious events such as bone fractures, spinal cord compression, or hypercalcemia (too much calcium in the blood).
When cancer spreads to the bone, it is called osteosarcoma or metastatic carcinoma. The cancer may spread to the bone by direct extension, or it may spread through the lungs, liver, and bone marrow. The most common type of cancer to spread to the bone is breast cancer, followed by lung, prostate, melanoma, and kidney cancer. Almost all cancers can metastasize to the bone, but some types of cancer spread to the bone more frequently than others. Breast cancer, for example, often spreads to the lumbar spine, femur, humerus, and ribs, while lung, ovarian, and prostate cancer tend to spread to the thoracic spine, pelvis, humerus, and ribs.
A tumor can grow in one location and eventually spread to other parts of the body, which is called metastasis. This is an important aspect of cancer, and it accounts for most of the deaths related to cancer. Metastases develop when cancer cells break off from the primary tumor and enter the bloodstream or lymphatic system, which are superhighways that carry fluids throughout the body. These highways then allow the cancer cells to travel to other organs, where they can grow and establish new tumors.
Once the cancer cells have reached a distant site in the body, they must survive and grow before they can establish a permanent lesion. In addition, the cells must avoid being killed by the local immune system. All of this is very difficult to accomplish, and only a small percentage of cancer cells are capable of doing so.
The most common place for a primary tumor to metastasize is to the lungs, followed by the liver. The bones, skeleton, and brain are less commonly affected by tumors that have metastasized.
In most cases, the cells that metastasize are identical to the original cancer cells. For example, if breast cancer spreads to the lungs, it will be treated as a stage IV cancer, because the lungs will contain the same type of cancer cells that originated in the breasts. However, sometimes doctors cannot determine where the cancer cells that spread from the primary tumor originated. In such cases, the cancer is considered to be of unknown origin and is treated as Carcinoma of Unknown Primary (CUP).
Research into metastasis has revealed that a variety of factors contribute to the success or failure of cancer cells in colonizing the secondary site. These factors include tumor-secreted substances, cellular characteristics, and the host environment. It is thought that the latter includes a metastatic niche, which provides attractants and growth factors for metastasizing cells. The identification of these factors will lead to better strategies for inhibiting metastasis, as well as identifying a subpopulation of cancer cells that are more likely to meetastasize.
Cancer cells that meetastasize to solid organs generally do so to the first organ they encounter during their dispersal from the primary tumor. This phenomenon is called organ tropism, and it has been shown to be influenced by the cellular and tissue properties of the organ in which the cancer cells metastasize. For instance, colorectal cancer has a high tendency to metastasize to the liver.