In Japan, mesothelioma is managed by occupational medicines. Mesothelioma is an aggressive cancer of mesothelial cells lining body cavities, in most cases caused by asbestos exposure decades earlier. Pleural mesothelioma accounts for roughly 80% of cases, peritoneal disease for 10-20%, and pericardial or tunica vaginalis tumors for under 1%.
Mesothelioma (ICD-10: C45) is a malignant tumor arising from mesothelial cells that line the pleura, peritoneum, pericardium, and tunica vaginalis. It is overwhelmingly caused by inhalation or ingestion of asbestos fibers — chrysotile (white), crocidolite (blue), and amosite (brown) — over years of occupational or environmental exposure, with crocidolite the most potent fibre type per unit dose. The malignant mesothelioma cell carries characteristic genetic alterations including loss of BAP1 (in roughly 60% of cases), CDKN2A deletions, NF2 mutations, and inactivation of the tumor-suppressor genes that normally restrain mesothelial proliferation. The latency from first asbestos exposure to clinical disease is typically 30-50 years, with shorter latency in heavier exposures.
The key symptoms of Mesothelioma are: Insidious onset of breathlessness, initially on exertion and progressing over weeks to months from accumulating pleural effusion compressing the lung., Persistent unilateral chest pain that is dull, aching, and gradually progressive — often the second most prominent symptom in pleural disease., Unintentional weight loss of 5-10 kg over 3-6 months, often the symptom that prompts presentation., Progressive fatigue and reduced exercise tolerance., Persistent dry cough or hoarseness from local invasion of mediastinal structures., Abdominal pain, bloating, and ascites in peritoneal mesothelioma, often mistaken for ovarian cancer in women and other intra-abdominal malignancy in men., Progressive abdominal distension with palpable masses in late peritoneal disease..
Diagnosis of mesothelioma is histopathological: a biopsy demonstrating malignant cells with characteristic immunohistochemistry confirms the diagnosis. The clinical pathway typically begins with persistent symptoms (dyspnea, chest pain, abdominal distension, weight loss), unexplained pleural or peritoneal effusion, or incidental imaging findings. Initial workup includes chest X-ray (often shows pleural thickening or effusion with characteristic shrunken hemithorax), contrast-enhanced CT of chest and abdomen (defines pleural thickening, mediastinal lymphadenopathy, and intra-abdominal disease), and pleural fluid sampling. Pleural fluid cytology has low sensitivity (around 30-40%) for mesothelioma; closed pleural biopsy adds little; video-assisted thoracoscopic (VATS) pleural biopsy is the gold standard with sensitivity over 90%. For peritoneal disease, laparoscopic biopsy with peritoneal cancer index (PCI) assessment is standard. Immunohistochemistry panel for diagnosis: positive markers include calretinin, cytokeratin 5/6, WT1, and D2-40 (podoplanin); negative markers include CEA, TTF-1, claudin 4, and BerEP4. BAP1 immunostaining (loss of nuclear staining) and MTAP (loss of cytoplasmic staining as surrogate for CDKN2A deletion) help distinguish malignant mesothelioma from reactive mesothelial hyperplasia, which can be morphologically indistinguishable. Staging uses IASLC TNM 8th edition for pleural disease and Peritoneal Cancer Index plus completeness of cytoreduction score for peritoneal disease. PET-CT is used to identify distant metastases. Genetic counselling and BAP1 germline testing is offered to younger patients (under 60), those with peritoneal disease, or those with family history of BAP1-related cancers. All confirmed cases should be reviewed at a specialist mesothelioma multidisciplinary team meeting before treatment.
Mesothelioma carries a serious prognosis but outcomes have improved meaningfully with modern systemic therapy. For pleural mesothelioma, median overall survival has risen from approximately 9-12 months (untreated) to 12-21 months with current first-line systemic therapy. Epithelioid histology has the best outcome (median OS 18-22 months), biphasic intermediate (12-15 months), and sarcomatoid the worst (6-8 months). The CheckMate 743 trial demonstrated 4-year overall survival of 17% with nivolumab-ipilimumab versus 10% with cisplatin-pemetrexed — a meaningful long-term survivorship that did not exist a decade ago. Peritoneal mesothelioma treated with CRS+HIPEC in selected patients achieves median OS of 30-90 months with 5-year survival approaching 50% at experienced centres. BAP1-mutated cases tend to be longer-surviving. Patients with germline BAP1 mutations have access to family screening and counselling. Long-term survivors (over 5 years) do exist, particularly with epithelioid disease, complete surgical cytoreduction, BAP1 mutation, and effective immunotherapy response. Most patients qualify for occupational disease compensation, which can ease financial impact during treatment.
Mesothelioma diagnosis and treatment require subspecialty multidisciplinary care. Patients should be referred immediately to a designated mesothelioma centre — typically a thoracic oncology unit affiliated with a specialist mesothelioma multidisciplinary team. Surgical management (P/D, CRS+HIPEC) must be performed by experienced surgeons at high-volume centres; outcomes are strongly dependent on centre volume and experience.
Find specialists →Acute treatment cycle (chemotherapy): 4-6 cycles over 12-18 weeks with response assessment by imaging after every 2-3 cycles. Immunotherapy: continued for up to 2 years or until progression or unacceptable toxicity. Surgery (P/D, CRS+HIPEC): hospital stay 5-14 days; recovery 6-12 weeks; return to function variable. Follow-up imaging every 3-4 months after treatment. Symptom management and supportive care continue lifelong.
Maintain mobility and gentle aerobic activity as tolerated. Structured exercise rehabilitation during and after treatment improves fatigue, dyspnea, and quality of life. Avoid heavy resistance training during severe thrombocytopenia or active bleeding. Pulmonary rehabilitation programs are valuable for pleural disease.
Choose a designated mesothelioma centre that performs at least 20-30 cases per year with documented outcomes. In the UK, all suspected mesothelioma is referred to a specialist multidisciplinary team. In the US, look for academic thoracic oncology centres with mesothelioma-specific programs. Surgery should be performed by thoracic surgeons or peritoneal surface oncology surgeons with documented experience in mesothelioma.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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