The Prognostic Role of TNM Staging Compared With Tumor Volume and Number of Pleural Sites in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive disease with a unique morphology and distribution. Because of its peculiar growth pattern, clinical staging is difficult. Quantitative assessment such as tumor volume (TV) was suggested as an alternative prognostic evaluation. In this study we aimed to compare the prognostic role of Tumor, Node, Metastases (TNM) clinical staging with that of alternative staging approaches on the basis of the use of 2 quantitative clinical parameters, TV and number of pleural sites (NPS), in MPM patients (pts). Our data confirmed the prognostic role of TNM, tumor size, TV, and NPS. However, the TV and NPS combination performed better than TV, NPS, and TNM alone as prognostic classifier. Considering different quantitative parameters and translating such an approach from research level to clinical practice could increase prognostic accuracy for MPM pts, and help clinicians choose the best therapeutic strategy. Background: Age, sex, stage, histotype, and surgery are the most recognized prognostic factors for malignant pleural mesothelioma (MPM). Tumor volume (TV) was suggested as an alternative prognostic evaluation. We aimed to assess the prognostic role of Tumor, Node, Metastases (TNM) versus TV and number of pleural sites (NPS). Patients and Methods: Information on stage, TV, and NPS was collected for 52 MPM patients (pts) at our institution from 2009 to 2012. Baseline computed tomography imaging was performed to define TNM, TV, and NPS. Pts were divided in 3 stage groups: early (I-II), III, and IV. A dedicated computer system calculated TV. Pts were divided in 2 groups according to mean baseline TV (483 cm(3)). NPS was defined on the basis of the NPS macroscopically involved by disease (1-3). The association between TNM, tumor size (T), TV, NPS, TV and NPS, and overall survival was assessed using Cox models adjusted for age, sex, histology, and treatment. Results: Most pts were male; mean age was 62 years. We showed an association between TV, TNM, and T. Stage III (hazard ratio [HR], 4.71; P = .02) and IV (HR, 7.40; P < .01), T3 (HR, 5.07; P < .01) and T4 (HR, 5.09; P < .01), TV > 483 cm(3) (HR, 3.47; P < .01) and NPS 2 (HR, 3.00; P = .08) and 3 (HR, 6.05; P < .01) were predictive of worse survival. However, the TV and NPS combination performed better than TV, NPS, and TNM alone as a prognostic classifier. Conclusion: We showed that TV is related to TNM staging and T, in particular. Improved prognostic performance might be achievable using quantitative clinical staging combining TV and NPS.