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.

Mesothelioma metastasis by cancer stage

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.

Where Does Mesothelioma Metastasize?

Metastatic mesothelioma can spread to several organs, such as the liver, lungs or spleen. Mesothelioma most often metastasizes to the:

  • Liver
  • Kidneys
  • Spleen
  • Adrenal glands

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

For many years, doctors considered pleural mesothelioma a localized disease. A 2012 study of 318 mesothelioma patients revealed that 55.4% of them had metastases to distant sites.

Researchers performed a similar review of 172 people who died of pleural mesothelioma. They found the most common sites for mesothelioma metastasis include:

  • Liver (55.9%)
  • Adrenal glands (31.3%)
  • Kidneys (30.1%)
  • The opposite lung (26.8%)

Cancer spreading to the brain and central nervous system is much rarer. In the past, researchers believed this occurred in only about 3% of postmortem cases. A 2022 study revealed that metastasis to the brain was closer to 5% in mesothelioma patients.

The retrospective study analysis looked at 164 pleural mesothelioma patients. About 67% had distant metastatic disease. The most common sites were bone (19%), viscera (14%), contralateral lung (35%) and peritoneum (22%).

In stage 4, pleural mesothelioma metastasizes to distant sites in more than 10% of cases. Cancer may also travel to other, rarer sites. A 2021 case study highlighted mesothelioma metastasis to the tongue causing oral symptoms.

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:

  • Liver
  • Visceral peritoneal lining
  • Abdominal lymph nodes

Less common sites are:

  • Lungs
  • Heart
  • Thyroid
  • Adrenal glands
  • Kidneys
  • Bone
  • Brain
  • Pancreas
  • Skin
  • Soft tissue
  • Appendix

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 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.

Metastatic Testicular Mesothelioma

As testicular mesothelioma progresses, it tends to spread from the tunica vaginalis. 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.

Stage

Doctors use a mesothelioma staging system to help gauge the progression of mesothelioma. 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 are the most at risk of metastasis. They may have distant metastases at diagnosis. 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.

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 are less aggressive and spread slower. This variant has a longer life expectancy.

Sarcomatoid and biphasic mesotheliomas spread faster to other areas of the body. This minimizes treatment options and reduces the expected life span.

Quick Fact:
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.

Response to Treatment

Early-stage patients may respond better to aggressive treatment. They may also have a reduced risk of developing metastatic mesothelioma.

Surgery can reduce the risk of metastasis. Removing tumors and cancer cells decreases the rate of spread. Chemotherapy and radiation therapy can delay or prevent metastasis. Anti-angiogenesis therapy also prevents tumor cell movement.

Radiation therapy is effective at preventing local recurrence. Doctors sometimes use it to treat tumors that develop in the chest wall.

Tumor Treating Fields also delays or prevents mesothelioma metastasis. This therapy uses alternating electric fields through skin adhesives worn throughout the day.

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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.

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.

Metastatic Liver Cancer

Mesothelioma cancer spread to the liver may cause:

  • Abdominal pain or discomfort
  • Bloating
  • Swelling of the legs
  • Jaundice

Metastatic Adrenal Cancer

Mesothelioma cancer spread to the adrenal glands, located on the top of each kidney, may cause:

  • Back pain
  • Muscle weakness
  • Abdominal pain or discomfort
  • Weight loss

Metastatic Kidney Cancer

Mesothelioma cancer spread to the kidneys may cause:

  • Pain in the side or back
  • Lumps on the side or back
  • Blood in urine
  • High blood pressure
  • Anemia

Metastatic Brain Cancer

Mesothelioma cancer spread to the brain can cause a variety of neurological symptoms, including:

  • Poor coordination or clumsiness
  • Memory loss
  • Severe headaches
  • Seizures
  • Personality changes
  • Vision changes

Metastatic Spleen Cancer

Mesothelioma cancer spread to the spleen is often asymptomatic, but may cause:

  • Severe abdominal pain
  • Rupture of the spleen

Treating Metastatic Mesothelioma

Treatment such as chemotherapy and radiation focuses on controlling cancer growth and its symptoms. It may also extend the life span of some patients. Palliative treatments can ease pain, improve quality of life and improve survival.

  • Chemotherapy can delay metastasis, improve survival and reduce pulmonary symptoms.
  • Radiation therapy can prevent local recurrence and treat painful chest wall metastases.
  • Anti-angiogenesis drugs can slow or stop mesothelioma metastasis.
  • Tumor Treating Fields can delay or prevent mesothelioma from spreading.
  • Medications and physical therapies can treat pain caused by distant metastases.

A mesothelioma specialist can recommend the best course of treatment after metastasis.

Clinical Trials Targeting Metastatic Spread

Many clinical research trials are publishing promising results for patients with metastatic mesothelioma. New therapies, such as immunotherapy and gene therapy, can improve patient survival.

Immunotherapy

Immunotherapy uses the body’s immune cells. It’s a newer treatment against metastasis. Researchers are studying more uses of this targeted therapy.

Gene Therapy

Manipulating DNA can treat and prevent certain diseases. Gene therapy fixes defective genes. This slows the spread of metastatic disease.

Multimodal Therapy

Mesothelioma specialists have tested newer treatments alongside traditional therapy. For example, immunotherapy before surgery may reduce the rate of metastasis.

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