THE IMPORTANCE OF SURGICAL STAGING IN THE TREATMENT OF MALIGNANT PLEURAL MESOTHELIOMA

Objectives: Progress in the therapy of malignant pleural mesothelioma is limited by the lack of an adequate staging system and controversy a bout prognostic factors. This surgical series was analyzed to determin e whether a new TNM staging system proposed by the International Mesot helioma Interest Group and certain prognostic factors could stratify p atients in future clinical trials. Methods: Thoracotomy was performed if computed tomographic scans showed resectable tumor confined to one hemithorax. Pleurectomy/decortication was done if visceral pleural tum or was minimal, and extrapleural pneumonectomy was done for more local ly advanced disease. Complete resection was defined as no gross residu al tumor. Adjuvant therapy was given as required by serial clinical tr ials. Patients had computed tomographic scans every 3 months until dea th. Prognostic factors were examined by log-rank and Cox regression an alyses. Results: From October 1983 to July 1994, a total of 131 thorac otomies were performed, resulting in 101 resections, 72 of which were complete. Extrapleural pneumonectomy was done in 50 patients and pleur ectomy/ decortication in 51. The ratio of men to women was 108:23. Med ian age was 63 years (range 32 to 80 years). Operative mortality was f ive of 131 patients (3.8%), three of 50 in the group having extrapleur al pneumonectomy (6%). Ninety-five of the 131 tumors were epithelial. Fifty-one of 89 patients (57%) having node dissections had diseased no des, 45 (50%) N2. By univariate analysis, type of resection, T and N s tatus, stage, histologic type, and adjuvant therapy, but not gender or age, significantly affected survival. Type of resection, stage, and h istologic type were significant in a multivariate analysis. Local recu rrence occurred mainly after pleurectomy/decortication, and distant me tastases developed after extrapleural pneumonectomy. Conclusions: (1) N2 nodal disease is more frequent than previously reported; (2) the pr ognostic importance of histologic type is confirmed; (3) both T and N status influence outcome, and the International Mesothelioma Interest Group staging system successfully identifies patients whose prognosis is poor; (4) despite more locally advanced disease in most patients,vi th extrapleural pneumonectomy, that approach provided better local con trol than pleurectomy/decortication but failed to improve survival bec ause of distant metastatic disease. Contrary to past practice, future clinical trials should stratify for histologic type, must control for TNM stage, and must consider the impact of type of surgical resection on the pattern of relapse.