DIFFUSE MALIGNANT MESOTHELIOMA

DIFFUSE MALIGNANT MESOTHELIOMA GENERAL THORACIC SURGERY CHAPTER 65 Diffuse malignant pleural mesothelioma • • • • Uncommon and lethal cancer. Currently no standard treatment. Asbestos exposure is major risk factors. Important for thoracic surgeons to be knowledgeable about mesothilioma – Because they are often called on to make the diagnosis and to recommend treatment. Epidemiology — Asbestos • Asbestos belongs to the family of silicate fiber. • Include two mineralogical groups: Amphibole and Serpentine. Amphibole fibers • Narrow and straight fibers. • Migrate through the lymphatics of pulmonary parenchyma and accumulate in interstitial space and subpleural region. • Crocidolite asbestos（blue asbestos）-The most associate with malignant mesothelioma. Serpentine fibers • Large, curly shaped fiber. • do Not travel beyond the major airways. • Chrysotile（white asbestos, the only member of Serpentin） -- More associate with lung cancer. Diffuse malignant pleural mesothelioma • • • • Peak age—6th decade. Men. Long latency period（at least 20 years）. Incidence—men 15/million, women 3/million. • Histology—Table 65-2. Clinical presentation • Nonspecific, Chest pain, dyspnea, pleural effusion, pericardial effusion, weight loss, cough, anorexia, weakness, fever, hemoptysis. • Horner’s syndrome. • Spontaneous pneumothorax. Clinical presentation • • • • • Abnormal ECG– Sinus tachycardia (42%). Echocardiographic findings. No specific tumor marker. Rise serum hyaluronan. CA-125 (20%). Radiographic appearance • Chest-x ray— Variable and related to stage of tumor. • Large pleural effusion, pleural thickening, pleuralbased mass. • Encasement of lung and obliteration of pleural space. • Involve pericardium and pericardial effusion. • Chest wall invasion, invasion through diaphragm. • CT— Most accurate noninvasive way to stage. • PET scan. Diagnosis • • • • • • • • Thoracentesis, cytology（positive rate 30-50%）. Percutaneous pleural biopsy. Thoracoscopy. Open pleural biopsy. AVOID Exploratory thoracotomy. Bronchoscopy. Meidastinoscopy. Bone scans. Staging • Not an accurate, universally accepted staging system. • Butchart (1976). Table 65-3. • TNM system. Table 65-4. • Liver is the most common site of distal metastasis, the contralateral lung is second. Treatment • Patient with malignant mesothelioma face a dual problem— Control of the locoregional tumor throughout the course of their disease, prevention of distant metastases as late manifestation of their cancer. • Choice of treatment – Location and extent of he tumor, the general medical condition of patient. • Surgery, radiation, chemotherapy, immunotherapy, supportive care. Radiation therapy • Difficult to evaluate the success of radiation therapy as the only treatment. • Usually given in conjunction with surgical resection or chemotherapy. • Limited by the volume of primary tumor that invole entire hemithorax, proximity of the tumor to many vital structures that intolerant high doses of radiation. • 4500 cGy. • Adjuvant treatment after surgical resection of gross tumor. Chemotherapy • Table 65-5. • Combination treatment. Table 65-6. • Response rate 30-40% Immunotherapy • Interferon– As antiproliferative effect on mesothelioma cell line. • Human interferon-α-2a combined with mitomycin C. • Interferon-γ – As an intrapleural treatment in early-stage diaseas（40x106U infused into pleural space twice weekly for 2 months）, 56% response. • Intrapleural interleukin 2. Intrapleural gene therapy • Herpessimplex virus thymidine kinase （HSVtk）gene– Transfer to tumor via adenovirus. • Administration of antiviral drug– Ganciclovir– Led the tumor death. Surgery • Still the mainstay of treatment. • Three operation– (1). Extrapleural pneumonectomy. （pleuropneumonectomy） (2). Pleurectomy-decortication. (3). Palliative limited pleurectomy. Extrapleural pneumonectomy • En bloc resection of pleura, lung, ipsilateral hemidiaphragm, pericardium, • Value– Controversial. • Operative mortality 6- 30%. • Preoperative CT, lung function, ventilationperfusion scan, cardiac function evaluate. Pleurectomy-decortication • Remove all gross pleural disease, without removing underlying lung. • Also remove hemidiaphragm and pericardium. Palliative limited pleurectomy • Resection parietal pleura to control pleural effusion. • Thoracoscopy and talc poudrage — High effective in controlling effusion.