Mesothelioma: Asbestos-Related Cancer — Symptoms, Diagnosis, and Treatment — Overview, Diagnosis & Treatment Options | MyMedicPlus

Malignant mesothelioma is a rare but aggressive cancer arising from mesothelial cells lining the body cavities. The pleura (lining of the lungs) is the most commonly affected site, accounting for 75-80% of cases, followed by the peritoneum (10-15%), pericardium (less than 1%), and tunica vaginalis (rare). Approximately 3,000 new cases are diagnosed annually in the United States, with significantly higher incidence in countries with historically high industrial asbestos use including the United Kingdom, Australia, and parts of Europe. The disease is almost always caused by prior asbestos exposure, with a latency period of 30-50 years between exposure and diagnosis, meaning that patients presenting today were typically exposed decades ago. Incidence is slowly declining in nations that banned asbestos but remains high in developing countries with ongoing industrial use. Mesothelioma is classified histologically into epithelioid (best prognosis), biphasic (mixed), and sarcomatoid (worst prognosis) subtypes.

Asbestos fiber inhalation or ingestion is the primary cause, accounting for approximately 80% of pleural mesothelioma cases. The carcinogenic potential differs markedly by fiber type: crocidolite (blue asbestos) and amosite (brown asbestos) are highly carcinogenic amphibole fibers that penetrate deeply into lung parenchyma and persist permanently; chrysotile (white asbestos, the most commercially used) is less carcinogenic. Erionite, a naturally occurring zeolite mineral found in volcanic rock formations in central Turkey, causes epidemic rates of mesothelioma in exposed villages. Germline BAP1 gene mutations cause the BAP1 tumor predisposition syndrome with markedly elevated mesothelioma lifetime risk and a tendency toward earlier onset. SV40 virus has been postulated as a co-carcinogen but this relationship remains controversial. Prior therapeutic chest irradiation is a rare cause. The long latency period (30-50 years) means occupational asbestos exposure in mining, insulation, shipbuilding, and construction in the mid-20th century drives current diagnoses.

Pleural mesothelioma presents insidiously over many months. The dominant early symptoms are progressive dyspnea (resulting from recurrent unilateral pleural effusion) and dull, non-pleuritic chest wall or shoulder pain. A dry, non-productive cough and constitutional symptoms — fatigue, weight loss, and low-grade fever — are common. As disease progresses, the pleural effusion may become loculated and the lung may become encased, causing severe restrictive ventilatory impairment. Peritoneal mesothelioma causes progressive abdominal distension from malignant ascites, diffuse abdominal pain, early satiety, and nausea. Bowel obstruction and omental cake formation occur in advanced peritoneal disease. Most patients present at an advanced local stage because the long latency period and non-specific early symptoms lead to delayed diagnosis, often with prior treatment for presumed benign pleural disease.

CT of the chest reveals pleural thickening, nodularity, circumferential pleural involvement, and pleural effusion. Tumor encasement of the lung is characteristic of advanced pleural mesothelioma. PET-CT identifies metabolically active disease and guides biopsy site selection. Pleural fluid cytology has very low sensitivity (approximately 32%) and is insufficient for definitive diagnosis; thoracoscopic (VATS) pleural biopsy with multiple samples from thickened pleura is required for adequate tissue. Immunohistochemistry: calretinin, WT-1, D2-40, and CK5/6 positivity with CEA, TTF-1, and Ber-EP4 negativity distinguishes mesothelioma from pulmonary adenocarcinoma. Molecular markers: NF2, BAP1 loss (IHC), and CDKN2A homozygous deletion (FISH) are common somatic alterations with diagnostic and prognostic relevance. Staging of pleural mesothelioma uses the IMIG/AJCC 8th edition TNM classification.

For unresectable pleural mesothelioma, the CheckMate 743 trial established nivolumab (anti-PD-1) plus ipilimumab (anti-CTLA-4) as the preferred first-line regimen, particularly for non-epithelioid histology, demonstrating superior overall survival over cisplatin-pemetrexed (median OS 18.1 versus 14.1 months, with 2-year OS of 41% versus 27%). Cisplatin plus pemetrexed (with mandatory folic acid and B12 supplementation to reduce toxicity) remains an alternative, especially for epithelioid histology. Bevacizumab may be added to cisplatin-pemetrexed in selected patients. For surgical candidates — typically those with early-stage (Stage I-II) epithelioid pleural mesothelioma and excellent performance status — pleurectomy-decortication (P/D, lung-sparing) followed by adjuvant chemotherapy is preferred over the more morbid extrapleural pneumonectomy (EPP). For peritoneal mesothelioma, cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (HIPEC) using cisplatin achieves median OS of 3-5 years in highly selected patients.

Asbestos exposure prevention is the only proven primary prevention strategy for mesothelioma. Banning asbestos use entirely — as more than 60 countries have done — eliminates the dominant risk factor. In countries where asbestos-containing materials remain in older buildings, safe encapsulation or abatement by trained professionals using appropriate respiratory protective equipment is mandatory before disturbance. Workers with documented prior asbestos exposure should inform their physicians, receive baseline chest CT, and may participate in surveillance programs. BAP1 germline mutation carriers require annual chest CT and other organ-specific cancer surveillance. No population-level screening test has been proven to reduce mesothelioma mortality. Occupational hygiene standards in industrial settings still using asbestos must be strictly enforced.

Anyone with a history of occupational asbestos exposure who develops new or progressive breathlessness, persistent chest wall pain, or a unilateral pleural effusion identified on imaging should seek urgent pulmonologist or respiratory medicine evaluation. These symptoms may appear 30-50 years after the exposure, so the latency should not provide false reassurance. Unexplained weight loss and fatigue in a person with known prior asbestos exposure — even remote — warrants prompt investigation including chest CT. Progressive abdominal distension with no obvious gastrointestinal explanation in someone with asbestos history should trigger evaluation for peritoneal mesothelioma. Patients diagnosed with mesothelioma should be evaluated at a specialized thoracic oncology center, as multidisciplinary assessment is essential for determining surgical candidacy and optimal systemic therapy selection.

Median survival for pleural mesothelioma is approximately 18 months with nivolumab plus ipilimumab and 14 months with cisplatin-pemetrexed. Epithelioid histology has significantly better prognosis than biphasic or sarcomatoid subtypes. Peritoneal mesothelioma treated with cytoreductive surgery plus HIPEC achieves median OS of 3-5 years in selected patients. Two-year OS with nivolumab plus ipilimumab is approximately 41%. Overall 5-year survival remains below 10%. The prognosis for Mesothelioma: Asbestos-Related Cancer — Symptoms, Diagnosis, and Treatment varies depending on severity at diagnosis, the patient's overall health, and how promptly treatment is initiated. With early diagnosis and appropriate management, many patients achieve good outcomes and maintain quality of life. Regular follow-up with healthcare providers is essential to monitor progress, adjust treatment as needed, and detect any complications early. Adherence to prescribed treatments and lifestyle modifications significantly improves long-term prognosis.