Malignant pleural mesothelioma: a population-based study of survival.

INTRODUCTION: This study characterizes the overall survival (OS) and variables affecting OS in patients with malignant pleural mesothelioma.
METHODS: A total of 9701 patients with malignant pleural mesothelioma, diagnosed from 1973 to 2006, were retrospectively analyzed using the population-based surveillance, epidemiology, and end results database.
RESULTS: The 6-month, 1-year, and 5-year OS were 55, 33, and 5%, respectively. Significantly adverse prognostic factors from univariate analyses included older age, male gender, higher tumor grade, nonepithelioid histology, higher stage, no cancer-directed surgery, and no radiotherapy. Race was not significant. Patients undergoing cancer-directed surgery and radiotherapy, when grouped by stage, histology, or grade, had the best median survival (versus radiotherapy or surgery alone or no surgery/radiotherapy). From Cox proportional hazards analyses, grade (range, 1-4) was associated with a hazard ratio (HR) of >1.5 (p < 0.0001), and not undergoing cancer-directed surgery was associated with a HR of >1.4 (p < 0.0001). Male gender and older age were also significantly adverse factors. Tumor histology (HR = 1.5) and nonlocalized stage (HR = 1.3) were significant in a Cox model omitting tumor grade. With grade and histology included in the Cox model, the HRs of histology and stage were of smaller magnitude and not significant.
CONCLUSIONS: From a population-based registry analysis of patients with malignant pleural mesothelioma, tumor grade and cancer-directed surgery seem to have the greatest impact on OS. Although being amenable to surgery likely reflects more indolent disease and/or better performance status and cardiopulmonary function, the significantly favorable impact of surgery, accounting for tumor grade, histology, and stage, may reflect a therapeutic benefit.