Multimodality Therapy for Malignant Pleural Mesothelioma: ConclusionPrevious staging systems for mesothelioma are of limited practical value because they are based on treatment strategies that do not include stratification of survival. The most commonly used staging system was proposed by Butchart et al in 1976, based on the treatment of 29 patients who underwent pleural pneumonectomy. According to this system, stage I disease is confined to the capsule of the pleural envelope, lung, pericardium, and diaphragm; stage II disease includes tumors extending into the chest wall, esophagus, heart, or contralateral pleura, with or without thoracic lymph node involvement; stage III disease includes tumors extending through the diaphragm into the peritoneum with positive extrathoracic lymph nodes; and stage IV disease classifies rare patients presenting with blood-borne metastases. This system does not reliably predict survival probability by stage.

A second system based on the international TNM staging variables has been proposed, but this has not correlated with patient survival. In malignant pleural mesothelioma, tumors tend to extend beyond their apparent clinical stage, complicating estimation of preresectional T stage. Tumor extent can be accurately assessed following complete gross resection (extrapleural pneumonectomy). The use of nodal designations such as Nl, N2, or N3 is not clinically meaningful in mesothelioma. In contrast to non-small cell lung cancer, lymphatic flow away from the tumor is inconsistent and therefore does not necessarily represent disease progression. The rarity of metastatic disease in patients dying of mesothelioma renders M status irrelevant in most cases.
The revised staging system proposed by us stratified the survival of 120 patients according to stage (Fig 4). Resectability, histologic type, and node status provide a basis for preoperative assessment and selection of appropriate patients for trimodality therapy. MRI has been found to be useful in estimating transdiaphragmatic and mediastinal invasion. New techniques for detecting lymph node involvement, including positron emission tomography scanning, could be used in conjunction with mediastinoscopy, laparoscopy, and thoracoscopy for more reliable preresectional staging.
Trimodality therapy has been successful in increasing survival of patients with negative-node and epithelial-type tumors, with the best survival seen in patients with both negative nodes and epithelial tumors. Stage-specific adjuvant therapies may form the basis of clinical trials examining this treatment strategy.