Metastasis and Progression of Mesothelioma

Mesothelioma, like most cancers, is progressive; it gets worse with time. Malignant mesothelioma progresses through stages I, II, III, and IV, and eventually metastasizes, or spreads to other parts of the body. This is what makes it so deadly.

For most patients with mesothelioma, the cancer will already have progressed to later stages, or even to metastasis by the time of diagnosis. Few people are diagnosed in the early stages or advance through each of them. Mesothelioma does typically progress to metastasis, although where the cancer will spread, and how quickly, depends on the individual and characteristics of the cells in the original tumor.

Mesothelioma Progression

Pleural mesothelioma is staged most often using the TNM system, which examines the growth of the original tumor, the spread of the cancer cells to lymph nodes, and metastasis. The cancer can be assigned as stage I, stage II, stage III, or stage IV, the latest and most advanced stage. Each stage describes how far the original tumor has expanded, whether the cancer has attacked the lymph nodes, and whether it has progressed to metastasis.

Progression may be different for each patient, but generally, the tumor begins in the pleura on one side of the chest cavity, either the pleura lining the lung or the pleura that lines the chest wall. From there the original tumor may grow into the pleura around the lungs or lining the chest wall, the diaphragm, or the area between the lungs. It may also grow into the chest wall, the lung, or the diaphragm.

Next comes the spread of cancer cells into the lymph nodes; usually those on the same side of the chest as the tumor are attacked first. From there the cancer may spread to more distant lymph nodes. The lymph nodes are collections of immune system cells that circulate lymph through the whole body. When cancer spreads to the lymph nodes metastasis is usually not far behind because the lymphatic system allows cancer cells to get to more distant parts of the body.

Factors Affecting Progression

Mesothelioma generally progresses quickly through the stages and to metastasis. Compared to other types of cancer it is aggressive and quick-moving. However, it progresses differently in different people. Cell type is one factor affecting its progress. Mesothelioma tumors have three main cell types: epithelial; sarcomatoid; and biphasic, a mixture of epithelial and sarcomatoid cells.

Sarcomatoid mesothelioma is the most aggressive and will metastasize and progress more quickly, because these cells do not adhere strongly to each other and can easily break off from the tumor and spread. Epithelial cells cling more strongly to each other, and therefore metastasis is slower with this type of mesothelioma. Biphasic tumors fall in between the two others.

Personal characteristics also determine how fast mesothelioma progresses. Younger patients and healthier patients are better able to withstand aggressive treatment, which can slow the progression of the cancer, and in rare cases even cure it.

Metastasis of Pleural Mesothelioma

Pleural mesothelioma, which attacks the tissue lining in the chest cavity, is most common. How it metastasizes will vary by patient, but studies show the most common locations for the cancer to spread. One found that most patients saw the spread of the cancer to the liver. The next most common organs were the adrenal glands, the kidneys, and the lung on the opposite side of the chest from the original tumor. Although less common, there have been instances of pleural mesothelioma metastasizing to the brain or spinal cord, to the bones, and one case even recorded metastasis to the tongue of a patient.

Metastasis of Peritoneal Mesothelioma

Peritoneal mesothelioma, the second most common form, begins in the tissue lining the abdominal cavity. Early progression of this cancer may see it spread to several areas of the abdomen, but metastasis only occurs later and outside the abdomen. Some metastatic sites recorded in peritoneal mesothelioma include the liver, the heart, the lungs, the adrenal glands, the kidneys, the thyroid, bones, the brain, and the skin.

Metastatic Liver Cancer

Liver cancer is one of the most common types of metastasis in mesothelioma patients. It occurs in more than half of patients who have metastatic mesothelioma. Some signs of secondary liver cancer include nausea, jaundice, decreased appetite and weight loss, fever, sweating, confusion, and pain in the upper right abdomen. Treatments for liver cancer include surgery and chemotherapy. Chemotherapy may be targeted, using surgery and imaging to deliver drugs directly to the liver.

Metastatic Heart Cancer

Metastasis to the heart is rare but possible. It has not been well studied because of its rarity, but it can happen with any type of cancer, including mesothelioma. Studies show that symptoms of a secondary cardiac tumor vary significantly. It may cause shortness of breath, low blood pressure, an irregular heartbeat, pericardial effusion, or congestive heart failure. Cardiac metastases often go undiagnosed until a patient dies.

Metastatic Lung Cancer

A common site of metastasis in pleural mesothelioma is the lungs, including the lung on the opposite side of the chest from where the cancer originated. This occurs in more than one quarter of patients with metastasis. Peritoneal mesothelioma may also metastasize to the lungs. Symptoms of lung cancer include chest pains, coughing with or without blood, shortness of breath, weight loss, and weakness. Treatment for these tumors is most likely to start with chemotherapy. Surgery may be used to remove as much of the cancer as possible if the tumors are not widespread throughout the lung.

Metastatic Adrenal Gland Cancer

Several cases have been recorded of mesothelioma spreading to the adrenal glands. It occurs in up to a third of the cases of metastasis of pleural mesothelioma, but it may also occur with peritoneal mesothelioma. The adrenal glands sit on top of each kidney. Cancer in the adrenal glands may cause back pain, abdominal pain, weight loss, or muscle weakness. It may also cause signs of adrenal sufficiency, a decrease in the hormones normally produced in the glands: low blood pressure, low blood sugar, and darkened skin.

Metastatic Kidney Cancer

Metastasis to the kidneys is possible, especially with peritoneal mesothelioma. Symptoms of cancer in the kidneys include blood in the urine, a mass on the side of the lower back, fatigue, lower back pain, loss of appetite and resulting weight loss, a fever, and anemia. Imaging scans and a biopsy can confirm that the cancer has spread to the kidneys.

Metastatic Thyroid Cancer

The thyroid is a gland in the neck that excretes hormones and impacts metabolism. It is a possible site of metastasis for both peritoneal and pleural mesothelioma. Signs of cancer in the thyroid may include a lump in the throat or neck, pain in the neck, changes to the voice or hoarseness, difficulty breathing or swallowing, and a persistent cough. Typical treatment for cancer in the thyroid involves surgery, often followed by radioactive iodine treatment. Iodine is absorbed by the thyroid, so radiation can be delivered directly to the site using iodine. Surgery of the thyroid may necessitate taking hormone pills to replace those normally produced in the gland.

Metastatic Brain Cancer

Studies show approximately 3 percent of mesothelioma cases result in metastasis to the central nervous system. There are many possible symptoms of metastasis to the brain, including poor coordination, headaches, memory loss, changes in sensation, personality changes, new seizures, vision changes, and vomiting. Treatment for this type of metastatic cancer usually involves surgery and radiation, which together can reduce symptoms and slow the growth of tumors.

Metastatic Skin Cancer

Mesothelioma that spreads to distant sites in the body may cause secondary skin cancer. Cancer cells can travel through the lymphatic system or through the blood to reach the skin. The symptoms of metastasis to the skin are lesions which may appear anywhere, usually red or pink raised bumps. A common location is near or on the surgical scar where the primary cancer was removed. Secondary skin lesions can be removed surgically.

Slowing the Progression of Mesothelioma

Mesothelioma is a quick and aggressive cancer that is only rarely curable. Most patients will experience a progression of the disease until it metastasizes. There are, however, steps that can be taken to slow progression in some patients. Eating well, getting exercise and enough sleep, and not smoking or drinking may help.

These lifestyle changes may help, although evidence that they will actually slow the progression is limited. But they improve a patient’s overall health. Healthier patients are eligible for more aggressive treatments and these can slow the progression of the disease and extend life.

Progression and metastasis of mesothelioma is mostly inevitable. A diagnosis of mesothelioma rarely comes with any hope of a cure. This is simply too aggressive a cancer, and a cancer that is too often diagnosed late, for cures to be likely. Most patients will experience the progression of the disease and metastasis that will most likely cause more symptoms, pain, and discomfort.

Metastatic cancer can be treated, but this is generally palliative care. Once cancer of any type has spread to distant parts of the body, it is impossible to eliminate it. Treatments like surgery, chemotherapy, medications, radiation, and other procedures can help patients feel better and may extend life a little bit.