When Does Mesothelioma Metastasize?
Mesothelioma metastasizes when tumor cells move to new areas. Distant metastases occur in 10% to 50% of stage 4 mesothelioma cases. Cancer cells can spread locally, regionally and distantly.
In stages 1, 2 and 3, cancer cells spread locally within the bodily cavity where they developed and regionally to lymph nodes. Only in stage 4 can mesothelioma metastasize to distant parts of the body.
It is generally more common for mesothelioma to continue spreading throughout the cavity where it originally formed. This is known in the medical field as a local spread.
Doctors detect cancer progression through diagnostic imaging tests. These include MRIs, PET or CT scans. Symptoms not generally associated with mesothelioma may be a signs cancer has spread. At that time, your doctor will perform tests or biopsies to look for distant metastases.
Learn More About How to Test for Mesothelioma
Where Does Mesothelioma Metastasize?
Metastatic mesothelioma can spread to several organs, such as the liver, lungs, kidneys, adrenal glands or spleen. Metastasis happens when cancer cells travel to distant sites. They may move through the bloodstream or lymph system. After mesothelioma cells have spread, they can invade organs and form secondary tumors.
Cancer cells reach the bloodstream through angiogenesis. This process forms new capillaries in the body from existing blood vessels. Researchers are studying ways to promote and block angiogenesis. These drugs are anti-angiogenic medications. They may be the key to slowing or halting the spread of cancer.
Drugs in clinical trials for mesothelioma metastasis include semaxanib (SU5416), thalidomide and tetrathiomolybdate. In studies, the three medications have stabilized the disease.
Metastatic Pleural Mesothelioma
Mounting research has shown that pleural mesothelioma spreads to distant organs. But for many years, doctors believed pleural mesothelioma was primarily a localized disease.
Research on Pleural Mesothelioma Spreading
- 2022 Study: A retrospective study revealed that metastasis to the brain occurs in 5% of mesothelioma patients. In the past, researchers believed this occurred in only about 3% of postmortem cases. Of 164 pleural mesothelioma patients, about 67% had distant metastatic tumors. The most common sites were bone (19%), viscera (14%), contralateral lung (35%) and peritoneum (22%).
- 2021 Report: A case report highlighted mesothelioma metastasis to the tongue that resulted in oral symptoms.
- 2012 Study: A study of 318 mesothelioma patients revealed that 55.4% of them had metastases to distant sites.
- 1991 Review: Researchers performed a review in 1991 of 172 people who died of pleural mesothelioma. They found the most common sites for mesothelioma metastasis include the liver (55.9%), adrenal glands (31.3%), kidneys (30.1%) and the opposite lung (26.8%).
Cancer spreading to the brain and central nervous system is much rarer. In stage 4, pleural mesothelioma metastasizes to distant sites in more than 10% of cases.
If cancer has spread to distant parts of the body, treatment options tend to be palliative in nature. These therapies relieve symptoms and provide comfort rather than cure the disease.
Metastatic Peritoneal Mesothelioma
In the early stages, peritoneal mesothelioma does not spread beyond the peritoneal cavity. This area contains the stomach, spleen, liver, intestines and other abdominal organs.
The most frequent sites of peritoneal metastases include the liver, visceral peritoneal lining and abdominal lymph nodes. Less common sites include the lungs, heart, brain, bone and kidneys.
As the disease progresses, cancer cells spread to near and distant organs. About 50% of peritoneal mesothelioma cases have distant metastases found at autopsy.
Metastatic Pericardial and Testicular Mesothelioma
The local spread of pericardial mesothelioma usually involves the pleura, lung and mediastinum. Pericardial mesothelioma metastasizes in about 25% to 45% of cases. Frequent sites are the regional lymph nodes, lungs and kidneys.
As testicular mesothelioma progresses, it tends to spread from the tunica vagin*lis. Target sites are retroperitoneal lymph nodes followed by inguinal and iliac lymph nodes. Metastasis in this variant is rare. When it occurs, it spreads to thoracic and lumbar vertebrae, omentum, liver and lungs.
What Other Factors Influence Metastasis?
Factors such as cancer stage, tumor cell type and response to treatment can influence metastasis. Some patients may have a lower risk if they have an early-stage diagnosis with a favorable cell type that responds well to treatment.
Factors Influencing Metastasis
- Cell Type: The rate at which cancer grows and spreads depends in part on the cellular makeup of the tumor. Tumors with an epithelial makeup spread slower. Sarcomatoid and biphasic mesotheliomas spread faster to other areas of the body.
- Response to Treatment: Early-stage treatment may reduce the risk of developing metastatic mesothelioma. Removing tumors and cancer cells decreases the rate of spread. Chemotherapy and radiation therapy can delay or prevent metastasis. Anti-angiogenesis therapy also limits tumor cell spreading. Tumor Treating Fields also delays or prevents mesothelioma metastasis. This therapy uses alternating electric fields through skin adhesives worn throughout the day.
- Stage: Patients diagnosed with mesothelioma at stage 1 or stage 2 have the least risk of metastasis. They also have the best prognosis, living around two to three years. Patients diagnosed with mesothelioma at stage 3 or stage 4 mesothelioma are the most at risk of metastasis. They may have distant metastases at diagnosis.
Doctors use a mesothelioma staging system to help gauge the progression of mesothelioma, and metastasis happens in stage 4 mesothelioma. This is the most difficult stage to treat because the cancer is spreading into vital organs. At this stage of development, treatment includes palliative, symptom-controlling care. This leads to a life expectancy of less than a year.
Learn More About Mesothelioma Staging
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What Are the Symptoms of Metastatic Mesothelioma?
Symptoms of metastatic mesothelioma include abdominal pain, changes in blood pressure or memory loss, among others. It can be difficult for doctors to detect when mesothelioma has metastasized. Distant spread occurs late in cancer development. It doesn’t always cause noticeable symptoms.
Symptoms Indicating Location of Metastasis
- Adrenal Glands: Spreading to the adrenal glands, located on the top of each kidney, may cause back pain, abdominal pain, muscle weakness and weight loss.
- Brain: Metastasis to the brain can cause a variety of neurological symptoms, including poor coordination or clumsiness, memory loss, severe headaches, seizures, personality changes and vision changes.
- Kidney: Cancer spreading to the kidneys may cause lumps or pain in the side or back, blood in urine, anemia and high blood pressure.
- Liver: Mesothelioma cancer spread to the liver may cause abdominal pain or discomfort, bloating, swelling of the legs and jaundice.
- Spleen: Spreading to the spleen is often asymptomatic, but may cause severe abdominal pain or a rupture of the spleen.
If metastatic cancer symptoms arise, they usually affect the new location. Some symptoms of mesothelioma metastases mimic common symptoms of mesothelioma and other cancers. Doctors often discover metastases by chance after imaging scans or other tests.
Treating Metastatic Mesothelioma
Treatment with chemotherapy can delay metastasis, while radiation therapy may prevent local recurrence. Anti-angiogenesis drugs can slow or stop mesothelioma metastasis.
In combination with chemotherapy, Tumor Treating Fields can delay or prevent mesothelioma from spreading. Immunotherapy is a newer treatment against metastasis. Receiving it before surgery may reduce the rate of metastasis.
A mesothelioma specialist can recommend the best course of treatment after metastasis. Medications and physical therapies can treat pain caused by distant metastases.
In addition to location and cell type, life expectancy may be affected by patient factors such as age and overall health, as well as available treatment options in each specific case. Life span is also affected by the cancer’s stage of development.
