Malignant mesothelioma metastasis mean that the cancer has spread beyond the site of the tumor’s origin, limiting treatment options and negatively impacting life expectancy.
Table of Contents
Key Points
- Mesothelioma Metastasis occur when mesothelioma becomes more advanced.
- Depending on the type of mesothelioma, the cancer will spread to different organs.
- Mesothelioma Metastasis can significantly limit available treatment options.
Malignant mesothelioma has a reputation as an aggressive cancer because mesothelioma cells can grow quickly and spread throughout the body. Unfortunately, because the cancer has such a long latency period and non-specific symptoms, the correct diagnosis is often made only when the disease has already metastasized and reached a more advanced stage.
Metastatic mesothelioma is usually associated with stages3 and 4, which means that the cancer has most likely reached the lymph nodes and distant organs. At this point, patients may be limited to palliative treatment options and have a prognosis of about one year.
Mesothelioma Progression
One of the main reasons mesothelioma is considered so dangerous is how quickly the cancer can spread locally, regionally, and even throughout the body. Mesothelioma cancer can spread in a number of ways, but most often it involves the cancer cells moving through the bloodstream, lymph nodes, or lymphatic system.
Usually, mesothelioma is not considered metastatic until stage 3 and 4. In the earlier stages, patients may have limited spread of cancer cells into adjacent tissues, but this is usually quite localized. Regardless of the type of mesothelioma, stage 3 and stage 4 cancer is considered more advanced and more difficult or impossible to cure. As the cancer spreads, theprognosis becomes more dire because it is increasingly difficult to kill or remove cancer cells that have spread throughout the body.
Features Of Metastatic Mesothelioma
stage 3 Mesothelioma
- The spread is localized on one side of the body
- The tumor has spread to nearby organs and lymph nodes on the same side of the body
- Treatment options are more limited and may only be palliative
Stage 4 mesothelioma
- The tumor has spread to several organs, lymph nodes, blood vessels and even possibly bones or brain
- Usually only palliative treatment is available
Where Does Mesothelioma Metastasis?
Any type of cancer can spread anywhere in the body, and once it has started, it is much harder to control. In mesothelioma, there are certain organs and tissues that often develop secondary tumors as the disease progresses, including:
- Liver
- Adrenal glands
- Kidneys
- Spleen
Mesothelioma cells can also metastasize elsewhere, depending on where the primary tumors originally developed.
Pleural Mesothelioma Metastasis
Malignant pleural mesothelioma metastasis first develops in the lining of the lung or pleura. After exposure to asbestos, the fibers can become trapped in the inner or outer pleural membrane and eventually develop into tumors. Patients with pleural mesothelioma often have a shell-like growth in one lung when it first develops, which can then easily spread throughout the pleural cavity.
Patients diagnosed with pleural mesothelioma most often have an epithelial cell type. Epithelial cells are known to divide and grow quickly but are slower to metastasize because cancer cells tend to stick together.
In a clinical trial that ran from 1992 to 2016, researchers studied 165 patients with malignant pleural mesothelioma to gain a better understanding of how the disease typically spreads. More than 80% of the participants showed an epithelial cell type. The researchers found that during this time period, more than 60% of cases had more regional spread, such as pleural effusion and metastasis to other lungs, and about 30% also had cancer spread to the lining of the heart (pericardium).
Although distant spread was less common, the researchers noted that in this study they found a higher rate of unanticipated sites of metastasis. About 20% of patients experienced rare bone metastasis from mesothelioma, and as many as 3% of participants had symptomatic brain spread. These patients survived an average of 24 months after diagnosis.
Peritoneal Mesothelioma Metastasis
Mesothelioma tumors can also develop in the lining of the abdominal cavity (peritoneum), causing peritoneal mesothelioma. With only about 500 new cases each year, the development and spread of the disease is not as well understood as pleural mesothelioma.
Like pleural mesothelioma, many cases of peritoneal mesothelioma are also composed of epithelial cells. However, biphasic cells and occasionally pure sarcomatoid cells are also most commonly found in peritoneal mesotheliomas. Sarcomatoid mesothelioma metastasis is considered the most dangerous; these cells have a faster growth rate and do not clump together, making it easier for them to travel through the bloodstream and spread to more distant organs. Biphasic mesothelioma is a mixture of epithelial and sarcomatoid cells, and its potential for metastasis depends on which cell type predominates.
Studies have found that patients with peritoneal mesothelioma have more localized and regional metastasis than distant ones. More than 50% of cases usually spread to other organs in the chest wall and abdomen, such as the appendix, pancreas, and kidneys. In some cases, studies have found more aggressive spread to the lungs, thyroid, or heart. Similar to pleural mesothelioma, bone and brain metastasis are extremely rare and not well documented.
Pericardial Mesothelioma Metastasis
In general, pericardial mesothelioma is the most difficult to detect and correctly diagnose because it is extremely rare. Unfortunately, most of these patients are only diagnosed postmortem. Primary tumors develop in the pericardium or lining of the heart, accounting for only about 2% of all mesothelioma cases.
In some studies looking at metastatic cancer, researchers have found that cancer cells can spread through the heart and pulmonary artery, which ultimately allows the cancer to progress more aggressively throughout the body. In some cases, new tumors have been found in the lungs, chest wall, abdominal cavity and lymphatic system.
Symptoms Of Mesothelioma Progression
As with any metastatic disease, as the cancer spreads and affects other organs and parts of the body, mesothelioma patients will develop new and worsening symptoms. The nature and frequency of these symptoms will depend on where the cancer has spread and the size of the new tumors.
Symptoms of Metastatic Mesothelioma
- Difficulty breathing
- Chest pain and tightness
- Abdominal and/or back pain
- Dysphagia (difficulty swallowing)
- Abdominal swelling
- Pleural effusion or peritoneal effusion (accumulation of fluid in the lungs or chest)
- Weight loss
- Bone fractures
Patients who experience worsening symptoms will also experience worsening overall health and will have a harder time tolerating the aggressive treatment usually recommended for mesothelioma.
Treatment Of Mesothelioma Metastasis
As the cancer spreads and symptoms worsen, so does the expected survival time. In these more advanced stages of cancer, patients survive only about a year on average, or even less if they have more severe metastases.
The goal of cancer treatment is to stop the spread of cancer, control the rate of cancer growth, and kill tumor cells. But with metastatic mesothelioma, it is often too late for patients to undergo curative treatment. With further spread, treatments such as surgery are no longer suitable as they become too dangerous for the patient. Other standard treatments such as chemotherapy or radiotherapy may still be recommended, but aspalliative treatment to help reduce symptoms and improve quality of life.
However, even in these advanced stages of the disease, clinical trials may be available to potentially prolong survival. New treatments such as photodynamic therapy and immunotherapy have shown promise even for patients with severe metastatic mesothelioma, extending survival to three years or more in some patients. It is important for patients to work with a mesothelioma specialist to determine the best treatment plan for their case.