Mesothelioma Overview
Mesothelioma is a form of cancer that affects the thin tissue lining surrounding internal organs, known as the mesothelium. Asbestos exposure is the primary cause of mesothelioma. This overview explains the major types of mesothelioma, how asbestos exposure leads to the disease, and the unique characteristics of each type.
Mesothelioma develops decades after asbestos exposure, making early detection difficult and diagnosis often delayed.
Common Types of Mesothelioma
Mesothelioma is classified based on where the cancer develops in the body. The most common location is the pleura, the lining around the lungs. Another major site is the peritoneum, the lining of the abdominal cavity. Less commonly, mesothelioma can develop in the tissues surrounding the heart (pericardium) or the testicles (tunica vaginalis).
Pleural Mesothelioma
Pleural mesothelioma affects the lining of the lungs and chest wall and accounts for 80% to 90% of all mesothelioma cases. Symptoms may include chest pain, dry cough, fatigue, and shortness of breath.
Asbestos fibers can lodge in the pleura, causing scarring and inflammation that eventually lead to tumor formation. Diagnosis typically involves imaging tests and biopsies. Treatment options include chemotherapy, surgery, and radiation therapy.
Pleural mesothelioma is staged from 1 to 4. Stage 1 is confined to the pleura, while stage 4 indicates spread to distant organs such as the liver, bones, diaphragm, heart, or central nervous system. Approximately 2,500 people are diagnosed with pleural mesothelioma each year.
Peritoneal Mesothelioma
Peritoneal mesothelioma affects the lining of the abdomen. Asbestos fibers may be inhaled or ingested and become trapped in the peritoneum. Symptoms include abdominal pain, swelling, nausea, and weight loss.
This type accounts for 10% to 15% of mesothelioma cases. The cancer develops when asbestos fibers irritate the peritoneal lining, causing inflammation and cellular damage.
The Peritoneal Cancer Index (PCI) is the most common staging system. The abdomen is divided into 13 regions, each scored from 0 to 3. Total scores determine the stage: Stage 1 (PCI 1–10) is least advanced; Stage 4 (PCI 31–39) is most advanced.
Epithelioid Mesothelioma
Epithelioid mesothelioma arises from epithelial cells and represents 50% to 70% of all mesothelioma diagnoses. These cells line internal structures and cavities. Asbestos exposure can cause mutations in these cells, leading to cancer.
Symptoms may include fever, loss of appetite, abdominal pain, swelling, and fluid buildup around the lungs or abdomen. Severe symptoms often appear in later stages. Epithelioid mesothelioma generally responds better to treatment and has a longer life expectancy than other types.
Sarcomatoid Mesothelioma
Sarcomatoid mesothelioma is the rarest and most aggressive form of malignant mesothelioma. It develops in the pleura and arises from sarcomatoid cells found in connective tissues such as tendons, bones, and nerves.
Symptoms may take 10 to 50 years to develop and include coughing, shortness of breath, chest pain, and later-stage symptoms such as coughing up blood, hoarseness, weight loss, nausea, vomiting, fatigue, and weakness. Treatment options include surgery, chemotherapy, and radiation, but outcomes are generally poorer due to treatment resistance.
