Pleura

Grade GX Grade cannot be assessed (Undetermined grade) G1 Well-differentiated (Low grade) G2 Moderately differentiated (Intermediate grade) G3 Poorly differentiated (High grade) G4 Undifferentiated (High grade) ||
 * **Epidemiolgy:** || Every year close to 3,000 people die from mesothelioma in the United states alone. Most of these individuals worked around asbestos for many years, some parts of the world have natuallry acouring asbestos, and in these areas the incidence of mesothelioma is higher. Men present with mesotheliomas more often than women, however this may be due to the fact that men were also more likely to have worked around asbestos than women. ||
 * **Etiology:** || Though other links are being looked for the only major link to plural mesothelioma is exposure to asbestos. 1 ||
 * **Signs & Symptoms:** || Shortness of breath and a heavy feeling in the chest area are the two main signs and symptoms, these are common symptoms of other illnesses and are often not taken with the seriousness they deserve which is why many cases are not caught in their earlier stages. Individuals with asbestos in their background will have regular screenings monitoring changes in the lungs. 7 ||
 * **Diagnostic Procedures:** || * Symptoms often resemble those of other, less serious conditions and generally do not arise until 20 to 50 years after the initial asbestos exposure occurred. Tumors may develop in any part of the mesothelium or even between organs. As a result, this cancer can be challenging to locate and diagnose. 1
 * General health work-up with checking for risk factors (asbestos exposure)
 * Imaging tests use x-rays, radioactive particles, or magnetic fields
 * Imaging tests may be done for a number of reasons, including to help find a suspicious area that might be cancerous, to learn how far cancer may have spread, and to help determine if treatment has been effective. ||
 * **Histology:** || Histological types: 1
 * Epithelial
 * Epithelial cells are the most commonly identified cell type
 * Sacomatous
 * Sarcomatoid cells are the least frequently occurring cells
 * Often resembling a spindle in shape.
 * Mixed
 * Tumors may also be comprised of both epithelioid and sarcomatoid cells
 * It is necessary for histopathologists to take multiple samples from randomized locations throughout the tumor for an accurate diagnosis. ||
 * **Lymph node drainage:** || * The pleural surfaces are rich in lymphatic channels 2
 * Drain into the hilum and connect to the veins and arteries
 * Drainage flows from nodes between the ribs to the parasternal, paravertebral and internal mammary nodes, then to the thoracic duct ||
 * **Metastatic spread:** || Mesothelioma spreads by direct extension, seeding throughout the pleural space (fissures, diaphragmatic and pericardial), through the chest wall, and into the mediastinum, peritoneum and lymph nodes. Mesothelioma is known for metastasizing to uncommon sites, and has been known to metastasize to the brain, spine, prostate, thyroid, and retroperitoneal lymph nodes. 5 ||
 * **Grading:** || The American Joint Commission on Cancer recommends the following guidelines for grading tumors: 6
 * **Staging:** || The oldest staging system and the one most often used is the Butchart System which is based mainly on the extent of primary tumor mass and divides mesotheliomas into four stages. The more recent TNM system considers variables of tumor in mass and spread, lymph node involvement, and metastasis. The Brigham System is the latest system and stages mesothelioma according to resectability (the ability to surgically remove) and lymph node involvement. 5

Butchart System – extent of primary tumor mass
 * Stage I: Mesothelioma is present in the right or left pleura and may also involve the diaphragm on the same side.
 * Stage II: Mesothelioma invades the chest wall or involves the esophagus, heart, or pleura on both sides. Lymph nodes in the chest may also be involved.
 * Stage III: Mesothelioma has penetrated through the diaphragm into the lining of the abdominal cavity or peritoneum. Lymph nodes beyond those in the chest may also be involved.
 * Stage IV: There is evidence of metastasis or spread through the bloodstream to other organs.

TNM System — variables of T (tumor), N (lymph nodes), M (metastasis)
 * Stage I: Mesothelioma involves right or left pleura and may also have spread to the lung, pericardium, or diaphragm on the same side. Lymph nodes are not involved.
 * Stage II: Mesothelioma has spread from the pleura on one side to nearby lymph nodes next to the lung on the same side. It may also have spread into the lung, pericardium, or diaphragm on the same side.
 * Stage III: Mesothelioma is now in the chest wall, muscle, ribs, heart, esophagus, or other organs in the chest on the same side with or without spread to lymph nodes on the same side as the primary tumor.
 * Stage IV: Mesothelioma has spread into the lymph nodes in the chest on the side opposite the primary tumor, or extends to the pleura or lung on the opposite side, or directly extends into organs in the abdominal cavity or neck. Any distant metastases is included in this stage.

Brigham System: (variables of tumor resectability and nodal status) influenced primarily by stage and histologic characteristics. Other prognostic models include factors such as age, gender, performance status, presence of chest pain, anemia, or elevated platelet counts. 3 || Image courtesy of: Nocolaou N. Prevention and Management of Radiation Toxicity. In: Pazdur R, Coia LR, Hoskins WJ, Wagman LD, eds. Cancer Management: A Multidisciplinary approach [e-book]. 10th ed. CMPMedica; 2007. Available from: CancerNetwork. Accessed June 4, 2012. ||
 * Stage I: Resectable mesothelioma and no lymph node involvement
 * Stage II: Resectable mesothelioma but with lymph node involvement
 * Stage III: Unresectable mesothelioma extending into chest wall, heart, or through diaphragm, peritoneum; with or without extrathoracic lymph node involvement
 * Stage IV: Distant metastatic disease ||
 * **Radiation side effects:** || External-beam radiation therapy is not effective as the primary treatment for cancers of the pleura. Due to the close proximity of critical organs such as the heart and lungs, these organs can exhibit significant toxicity from treatment. Pulmonary toxicity can lead to contralateral pneumonitis. 3 ||
 * **Prognosis:** || The median survival for patients diagnosed with malignant plerual mesothelioma is generally poor, ranging from 4-18 months. The prognosis is
 * **Treatments:** || Most treatments for cancer of the pleura begin with surgery for local contol, along with combinations of chemotherapy and postoperative radiation therapy. The two most common operations performed are extrapleural pneumonectomy and pleurectomy-decortication. Trimodality therapy is growing in popularity and shows indications of an increased survival rate. 3 ||
 * **TD 5/5:** || When treating primary or malignant tumors of the pleura, it is important to monitor dose to vital organs such as the lungs, heart and, liver. 4
 * **References:** || # Pleural Mesothelioma. Pleuralmesothelioma.com. Available at: [|http://www.pleuralmesothelioma.com] . Accessed: June 2, 2012.
 * 1) Stinson D, Wallner PE. Principles and Practice of Radiation Therapy. 3rd ed. St. Louis, Missouri; Mosby Inc: 669.
 * 2) Hoppe RT, Phillips TL, Mack III M. Leibel and Phillips Textbook of Radiation Oncology. 3rd ed. Philadelphia Pa: Elsevier Saunders; 2010.
 * 3) Abeloff MD, Armitage JO, Niederhuber JE, Kastan MB, McKenna WG. //Abeloff's Clinical Oncology//. 4th ed. Philadelphia, PA: Churchill Livingstone; 2008.
 * 4) WorldPress. Mesothelioma Stages. Available at: [] . Accessed June 5, 2012.
 * 5) MedicineNet. Tumor grade. Available at: [] . Accessed June 5, 2012.
 * 6) Early Symptoms of Mesothelioma. Available at: [|http://www.mesotheliomasymptoms.com/early-symptoms-mesothelioma] .Accessed June 9, 2012 ||

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