Treatment of Mesothelioma - Diffuse Pleural Mesothelioma
Treatment
The lack of uniformity in approach and the small number of patients in most studies at present preclude standardization of the treatment of mesothelioma.
Mesothelioma Treatments
Traditional mesothelioma treatment options include surgery, chemotherapy and radiation therapy. Traditional treatments are also used to combat other types of cancer such as asbestos lung cancer, carcinomas, sarcomas, lymphomas, etc.
New mesothelioma treatment options include new chemotherapy agents, photodynamic therapy (PDT), immunotherapy, mesothelioma gene therapy and intensity modulated radiation therapy (IMRT).
Surgery
The role of surgery in managing diffuse pleural mesothelioma remains controversial, but there are an increasing number of thoracic oncologic surgeons who are operating for this disease. Nevertheless, overwhelming pessimism for curative surgical options continues in most centers that do not routinely deal with the disease, since the combination of effusive disease and bulky tumor renders surgical eradication virtually impossible. The disappointing long-term overall survival results, the historically high morbidity and mortality rates, as well as the propensity for local recurrences have forced many centers to abandon radical operations, except for the very rare localized situation.
The arguments regarding appropriate management of mesothelioma can have geographic differences. This is illustrated in a United Kingdom poll of chest physicians regarding diffuse malignant mesothelioma (DMM). Only 46% of the physicians surveyed would consider referral to a thoracic surgeon for radical resection (Butchart, personal communication). The French approach to the disease has been a concentration on detection of early stage I disease that is treated with intrapleural therapy, including interferon-gamma (IFN-<) with or without cisplatin.36a
Surgery is performed after this therapy only to improve local control, either by pleurectomy or extrapleural pneutreatment. 33,39,54,225 Epithelial cell type has been associated with a more favorable prognosis in most large series;1,10,39,63,127,170,225 the fibrosarcomatous type carries the worst prognosis, and the mixed type is intermediate.
10,63,127 Younger age at diagnosis has also been reported as a favorable feature,10,63 whereas no prognostic differences were found between men and women,10,63,225 particularly after adjustment for cell type.1,170 Absence of weight loss, lack of involvement of the visceral pleura, early stage, and epithelial cell type were shown to be favorable prognostic factors in a large group of 188 patients with pleural mesothelioma. 32 The negative prognostic impact of thrombocytosis first reported by Chahinian and colleagues62 has been confirmed in three other series.124a,225,226 The prognostic role of other factors (asbestos exposure or not, duration of symptoms, side of pleural disease, and pleural versus peritoneal involvement) is more contradictory at this time.
Other Types of Malignant Mesotheliomas
Mesotheliomas limited to other organs are extremely rare. About 120 cases of pericardial mesothelioma have been reported;299 this represents the most frequent primary malignant tumor of the pericardium and accounts for half of them.252 It has been reported at any age; there is a 3:1 male predominance.275 The tumor produces signs of pericardial effusion, often bloody, leading to cardiac tamponade and/or constriction of the vena cava and great vessels. Local spread as well as metastases involving the pleura, lung, mediastinum, or distant organs occurs in half the cases.267 Survival time is usually less than 6 months, although 2 patients treated with surgery and radiotherapy survived 1 and 5 years, respectively.252 The role of asbestos exposure has not been systematically explored, although it was strongly suggested in one report.24
Malignant mesothelioma of the tunica vaginalis testis ('adenomatoid tumor") presents as a scrotal mass, often associated with a hydrocele. In a review of 24 cases, median age was 61 (range 21 to 78) years, and asbestos exposure was documented in 6.8
Benign Mesotheliomas
Benign mesotheliomas usually are not related to asbestos exposure.
Solitary fibrous tumor of pleura is a neoplasm formerly referred to as benign fibrous pleural mesotheliomas. These fibrous tumors of the visceral or parietal pleura are often pedunculated and are unrelated to asbestos exposure. Pleural effusion is exceptional. Most are benign; although a malignant form does rarely occur. Clubbing and osteoarthropathy are common and are present in 20 to 50% of cases versus only 6% in malignant mesothelioma.51 Hyponatremia attributed to inappropriate secretion of antidiuretic hormone and hypoglycemia have been described.299 Surgery is curative. Microscopically, these tumors are well circumscribed fibromas with a variable collagenous matrix containing interweaving bundles of ovoid or spindle cells without atypia.26
Mesothelioma of the atrioventricular node is very rare (about 50 cases reported), usually minute or even microscopic.299 Partial or complete nodal heart blocks and/or sudden death are the major consequences of this tumor, which has the distinction of being the 'smallest one that can cause death."299 Two thirds occurred in females, and age ranged from an 8-month-old fetus to an 86-year-old woman.78
Adenomatoid tumors are benign mesotheliomas arising in or near the male or female genital tract organs, although occasionally more distantly in the peritoneum.74
Benign multi-cystic peritoneal mesothelioma affects mainly young females and produces cysts of variable size and number lined by a single layer of benign mesothelial cells. The major differential diagnoses are lymphangioma and ovarian cancer of low malignant potential.
The disease follows a benign course and is compatible with a normal life expectancy, requiring, occasionally, partial excision or decompression for relief of pain or other symptoms. The malignant potential is exceptional.223,234,301