Mesothelioma is a kind of cancer originating in the lining of internal organs called the mesothelium. It is a rare cancer, and there are three types: pleural mesothelioma, where the cancer is in the lining of the lungs; peritoneal mesothelioma, which starts in the abdominal lining; and pericardial mesothelioma, which is found in the lining of the sac that surrounds the heart.
Significance
The American Cancer Society estimates that in the United States, approximately two to three thousand new diagnoses of malignant mesothelioma are diagnosed yearly as of 2010. It is a rare disease, with the lifetime risk being approximately one in 770 people, says the American Cancer Society.
Signs and Symptoms
Pleural mesothelioma symptoms can include muscle weakness, swelling of the face and arms, fatigue, weight loss, difficulty breathing and pain in the lower back or the side of the chest, says the American Cancer Society. Symptoms of peritoneal mesothelioma are abdominal pain or distention, nausea and vomiting and weight loss. These symptoms do not always mean an individual has mesothelioma, but can lead to diagnostic tests that will provide more definitive diagnoses.
Diagnostic Tests
Mesothelioma and lung cancer can present with similar symptoms, says the National Cancer Institute. To diagnose mesothelioma, a physical exam is done to assess for any abnormalities, along with a chest X-ray. Blood tests are also performed, including a complete blood count and a sedimentation rate test. A biopsy is taken to provide a tissue sample for microscopic evaluation; this is done by either a fine-needle aspiration, thoracotomy or thoracoscopy, or a laparotomy. Bronchoscopy may be performed to look closely inside the lungs for any abnormal areas, according to the National Cancer Institute.
Staging Process
After a diagnosis of mesothelioma, the disease is staged. Staging involves using various tests to gain more information about the cancer, like the size of the tumor and whether it has spread anywhere else in the body. There is a standardized staging system, and the stage of the cancer helps direct treatment plans and prognosis. Staging tests listed by the National Cancer Institute include a chest X-ray, CT scan, MRI and endoscopic ultrasound.
Stages
Mesothelioma can be described as localized or advanced, with localized mesothelioma being Stage I. In this stage, the cancer is only in the chest wall lining; it may also be in the lining of the lung, diaphragm or the sac that covers the heart, says the National Cancer Institute. The cancer is only on one side of the body. Advanced mesothelioma comprises Stages II, III and IV. Stage II mesothelioma is diagnosed when cancer is in the chest wall lining and lymph nodes on the same side of the chest; it may also be in the pleural lining, diaphragm or covering on the heart. In Stage III, the disease has metastasized to the chest wall, the area between the lungs called the mediastinum, the heart or the lining of the abdomen. Stage IV is the last and most advanced stage, and in this stage, the cancer has spread to distant sites in the body.
