Traditional treatments are chemotherapy, following surgery which attempts to remove as much of the mass as possible. Chemotherapy is the first line of treatment following surgery. Single agents are no longer used in this disease, as there was less than a 20% responsiveness rate and was considered a poor result. Currently 2 agents are used with increasing response rates to up to as high as 44% survival over one year. Traditional agents are used, but what is of current interest is the novel drug combination of using Bevacitumab and Onconase. Innovative treatment is uisng Alimta (Pemetrexed) for pleural mesothelioma, and using photodynamic therapy (PDT). PDT is a fixed frequency light used to activate photosensitizing drugs that accumulate in body tissues. PDT is administered IV and in a matter of days the durg selectively concentrates in the cancer cells, and is rapidly eliminated by the normal cells. Doctors then use a laser light chosen for its ability to activate the photosensitizing agent using a fiberoptic device to control the laser light. Radiation therapy is used for patients who are not well enough to undergo a surgical procedure, or used in combination with surgery to ease symptoms such as shortness of breath, pain with breathing, or trouble swallowing. Radiation can be given externally to the effected area, or can be placed surgically using radioisotopes which is considered internal radiation therapy. There are currently 11 clinical trials underway in the US, with 16 total clinical trials being conducted worldwide.
The Butchart System is the oldest staging system, the more recent is the TNM system, and the latest system used is the Brigham System. The Butchart System describes Stage 1 as involving the lining of one lung and the diaphragm on the same side, Stage 2 involves invasion into the chest wall, esophagus, heart, or involving both lungs, with possibily lymph nodes in chest being involved. Stage 3 involves the diaphragm extending into the lining of the abdominal cavity or peritoneum, and may effect lymph nodes beyond those in the chest. Stage 4 is the final stages and involves mets or spread of cancer to other organs. The TMN System Stage 1 involves the lining of one lung, the pericardium or diaphragm on the same side with no lymph node involvement. State 2 shows involvement of lymph nodes to the lung effected on the same side. Stage 3 involves chest wall muscle, ribs, heart, esophagus or other organs of the chest on the same side of the primary tumor. Stage 4 involves spread of disease to lymph nodes in the chest on the opposite side of the primary tumor, extends into the lung opposite the primary tumor, or extends directly into the organs of the abdominal cavity or neck. Mets are included in this stage. The Brigham system focuses on the resectability of the mass surgically. Stage 1 is that the tumor is resectable and lymph nodes are not involved. Stage 2 is mass is resectable but lymph nodes are involved. Stage 3 is mass is unresectable and extends into the chest wall, heart, or through the diaphragm, peritoneum, with or without lymph node involvement. Stage 4 occurs when doctors discover mets of distant organs.
The 3 main subtypes are epitheloid which account to 50-70% of cases diagnosed, and has the best outlook to respond to treatment. The other 2 are mixed/biphasic, and sarcomatoid, which do not respond as well as the epitheloid. All 3 subtypes are treated the same, and traditional treatments are surgical removal of tumor, chemotherapy, and radiation therapy.
Clinical evaluation involves a complete history and physical, XRays of the chest and abdomen, pulmonary function studies, and CT or MRI of the chest and abdomen. Inconclusive studies are needle biopsy of fluid from either the fluid surrounding the lung to send to pathology, or needle aspiration of fluid in abdominal cavity to retrieve fluid to send to pathology. Both of these tend to be inadequate because there is a need to determind the cell type. There can be negative or inconclusive readings which account for 85% of all fluids tested, therefore this is rarely considered as a true diagnostic evaluation. Definitive diagnosis is made by obtaining tissue samples surgically by using a thoracoscopy/laproscopy to look directly at tumor and remove an adequate amount of tissue. Open biopsies such as these are done under general anesthesia and tissue samples are taken directly to a pathologist for review.
The 3 forms of mesothelioma listed by the NCI are the following: pleural mesothelioma which is the most common, with 3/4 of all cases involving the chest cavity. The second form is peritoneal mesothelioma, which accounts for 10-20 percent of cases which start in the abdominal cavity. The third form is pericardial mesothelioma, which occurs around the lining of the heart, and is very rare. The disease is very difficult to diagnose as the symptoms are non-specific, and the latency period of the disease manifesting itself is on an average 35-40 years from the time of exposure until symptoms are manifested. Symptoms can include pain in the lower back, the side of the chest, shortness of breath with the pleural form. Abdominal symptoms include belly pain, weight loss, nausea, and vomiting. Pleural effusion (fluid collecting between the lining of the lung and chest cavity) represents one of the most common symptoms of pleural mesothelioma.