The mesothelioma survival rate is different for different types of malignant mesothelioma. Mesothelioma is primarily caused by asbestos exposure, and may be referred to as “asbestos mesothelioma.” The mesothelium is the lining on the internal organs on which mesothelioma cancer cells form. Pleural mesothelioma is the most common kind.
The three major types of mesothelioma are epithelial mesothelioma, sarcomatoid mesothelioma, and biphasic mesothelioma (a combination of the first two types).
The rarest mesothelioma type
Sarcomatoid mesothelioma is the rarest mesothelioma type. Only 10% to 20% of mesothelioma patients have solely sarcomatoid mesothelioma. The cancer cells in this type of cancer are spindle shaped and overlapping. It forms in the support tissues like muscle, bone, and cartilage. The nuclei of the cells of this type are not as clearly defined as the nuclei in epithelial mesothelioma. Sarcomatoid mesothelioma may be localized to one tumor, or it may be spread to lymph nodes or to other parts of the body altogether, such as the lungs, the abdominal cavity, or the chest wall.
While epithelial mesothelioma cells originate in the cells that make up the membrane lining of the chest and abdominal cavities, sarcomatoid mesothelioma originates from “mesodermal” or connective tissues in the body. These tissues include muscle, fat, bone, and cartilage.
Diagnosis of sarcomatoid mesothelioma begins with biopsy of affected tissue. The symptoms of mesothelioma overlap with symptoms of other diseases, such as other types of lung cancer, and include shortness of breath, chest pains, and pleural effusion, which is the collection of fluid in the lining of the lung. The mesothelioma survival rate for sarcmatoid mesothelioma is not good. This type of cancer typically doesn’t respond well to the mesothelioma treatments developed for it (chemotherapy, radiation therapy, and surgery), and the prognosis is generally for one year or less of survival.
Asbestos exposure
However, the odds improve significantly the earlier the disease is diagnosed. Anyone who has asbestos exposure in their past, whether from encountering asbestos in a work environment or on the clothing of someone in the household who worked with asbestos, should inform their doctor so that if symptoms do come up (or if an early mesothelioma diagnosis technique should develop), the physician will know to include mesothelioma in the diseases to look for.
One hazard to accurate and timely diagnosis of mesothelioma is that the cells, with their long oval shape, resemble other types of cancer cells, particularly with cancers called sarcomas and carcinomas. Sarcomas usually appear in the kidney and other parts of the body. It is rare in the lungs. Only just over 1% of lung cancers are sarcomas. Pulmonary sarcomatoid carcinoma is the type of cancer that is most likely to be confused with sarcomatoid mesothelioma. It is more likely to strike men, and it is correlated with smoking. The symptoms of these two types of cancer are the same, too, adding to the confusion.
High-grade sarcoma is another type of cancer that is sometimes confused with sarcomatoid mesothelioma. If high-grade sarcoma spreads to the surface of the lungs, it can be hard to differentiate, but there are pathologists who specialize in diagnosing mesothelioma who know how to tell the two apart. Anyone with asbestos exposure who is diagnosed with sarcoma or carcinoma should obtain a second opinion and ensure that the pathologists have experience in differentiating mesothelioma from other types of cancer. While the mesothelioma survival rate for this type of disease is low, the odds are better the earlier it is identified correctly.
The type of malignant mesothelioma a person is diagnosed with can affect their treatment options. The mesothelioma stage is important too. There are almost always clinical trials being conducted that depend on the type of mesothelioma, the stage, and other factors, such as whether the patient has undergone mesothelioma treatments and whether they have worked or not.
Desmoplastic mesothelioma
There is a subtype of sarcomatoid mesothelioma called desmoplastic mesothelioma that is considered the most difficult type of mesothelioma to diagnose. The cancer cells for this type of disease can easily be misdiagnosed as benign tissue. Experts in mesothelioma say that a needle core biopsy is not sufficient to diagnose this type of mesothelioma.
The three basic types of mesothelioma are treated in much the same way. The treatments are based on the locations of the cancer cells, mesothelioma stage, the patient’s age, general health, and the patient’s wishes. Though the prognosis for sarcomatoid mesothelioma is worse than for the other types, once it is positively identified, there are many things that hospitals and cancer centers can do. Some patients may wish to take an aggressive approach to the treatment, and patients who are older and have other health problems to deal with may opt for mostly palliative care. Generally a health care team, made up of an oncologist, nurses and other professionals, a pathologist, and the patient will work together to determine the best course of action to take.
The diagnosis
Diagnosis of sarcomatoid mesothelioma will involve non-invasive tests like x-rays, CT scans, and MRI scans, as well as biopsies and sometimes other surgical exploration as well. During a biopsy, cancer cells are taken from a number of different locations on the tumor so that if the tumor consists of different types of malignant cells, the pathologist will be able to pick up on that. Tissue samples are fixed by the pathology lab so that they can be stored indefinitely, and the pathologists can go back to those samples multiple times to shave off small, thin slices of tissue to examine under a microscope using various staining techniques.
The cells in the tissue samples will also be tested for the presence of molecules like oncoproteins that are produced by certain cancer cell types. Because sarcomatoid mesothelioma cells can so easily be confused with sarcoma and carcinoma cells, microscopic examination is not enough to definitively determine the nature of the cells. Malignant mesothelial cells produce specific kinds of proteins that may be present on the cell surfaces. Histologists, or cell specialists, examine these proteins to accurately pinpoint the type of cancer that is present. Adenocarcinoma, a type of cancer that is easily confused with sarcomatoid mesothelioma, produces mucin, while the sarcomatoid cancer cells do not. Markers like dyes, enzymes, or colloidal gold help histologists localize proteins and antigens on cells of the tissue samples taken.
The treatment options for mesothelioma not only depend on whether it is epithelial, sarcomatoid, or biphasic mesothelioma, but also on where in the body the cancer is located. The mesothelioma stage is also important in determination of treatment options. The more advanced the disease is, the more it has spread throughout the body. Sometimes the tumor is very self-contained, and other times it has spread. The first place it usually spreads to are the lymph nodes in the vicinity of the tumor. However, the disease can spread to the lung itself, or to more distant organs.
Peritoneal mesothelioma is more likely to be sarcomatoid mesothelioma. Sarcomatoid cells respond differently to treatment than do epithelial mesothelioma cells. The chemotherapy used to fight epithelioid mesothelioma sometimes contain an enzyme that sarcomatoid cells resist. The fact that pure sarcomatoid mesothelioma is so rare is another reason that doctors find it more difficult to treat: the body of knowledge of this type of mesothelioma is not as extensive as it is with other types. Additionally, sarcomatoid cancer cells are more aggressive than other cancer cells. Not only will tissue samples show the odd, long oval shape with clumping and overlapping, but there will be cells in various stages of mitosis, or cell division.
Treatment for sarcomatoid mesothelioma is based on managing pleural effusions, the use of radiation therapy, and evaluation for possible surgical removal of tumors. Mesothelioma specialists will be able to find out if a patient is eligible for any clinical trials that may help his or her prognosis.
Pleural efflusions
Managing pleural effusions is usually a matter of thoracocentesis (withdrawing fluid from the chest cavity) or pericentesis (withdrawing fluid from the abdominal cavity). The patient’s response to removal of this excess fluid will determine if this treatment is repeated. Generally, managing pleural effusions is important to the patient’s comfort and for preventing a condition called “trapped lung.” But repeated withdrawal of fluid can cause the fluid to become difficult to drain, and can increase the risk of lung infection.
Radiation therapy may be done to control tumor growth, and as a form of palliative therapy. In some cases it causes regression of the disease. But there is so far no evidence that radiation therapy by itself increases the mesothelioma survival rate. Therefore, radiation therapy is usually part of a multi-pronged approach for treating sarcomatoid mesothelioma. It is usually combined with so-called debulking surgery and can help alleviate symptoms.
The most common surgical intervention with sarcomatoid mesothelioma is debulking surgery. A procedure called extra pleural pneumonectomy (EPP) is one surgical procedure used. It involves resectioning of the lung, the pleura, the pericardium, diaphragm, and local lymph nodes. A procedure called pleurectomy / decortication (P/D) is another option for those who for whatever reason aren’t good candidates for EPP. However, the P/D procedure does not always remove all the tumor. The survival benefit of P/D is not yet really known. EPP is the preferred treatment option, though it is a more demanding surgery. Some doctors can administer high dose radiotherapy along with EPP, which is known to reduce local recurrence and improve survival if the disease is in a relatively early stage.
Mesothelioma survival rates are generally low, but for those who are otherwise healthy and who are diagnosed with sarcomatoid mesothelioma at a relatively early stage, treatment is promising, and new treatments are coming online all the time. Clinical trials and advanced therapies at cancer treatment centers are rapidly broadening the base of knowledge about all types of mesothelioma.