Radiotherapy in Pleural Malignant Mesothelioma: Why not! in Regard to Scorsetti et al. ( Int J Radiat Oncol Biol Phys 2010;77:942–949); Krayenbuehl et al. ( Int J Radiat Oncol Biol Phys 2010;78:628–634)

Abstract

To the Editor: We read with interest the articles by Scorsetti et al. ( 1 Scorsetti M. Bignardi M. Clivio A. et al. Volumetric modulation arc radiotherapy compared with static gantry intensity-modulated radiotherapy for malignant pleural mesothelioma tumor: A feasibility study. Int J Radiat Oncol Biol Phys. 2010; 77: 942-949 Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar ) and Krayenbueh et al. ( 2 Krayenbuehl J. Hartmann M. Lomax A.J. et al. Proton therapy for malignant pleural mesothelioma after extrapleural pleuropneumonectomy. Int J Radiat Oncol Biol Phys. 2010; 78: 628-634 Abstract Full Text Full Text PDF PubMed Scopus (35) Google Scholar ). Although the improving technology allows a better target coverage and a dose sparing to organs at risk in pleural malignant mesothelioma (PMM), we believe that physiopathological bases that should support a role of radiotherapy (RT) in PMM are very weak. •Regarding post pleurectomy/decortication (P/D) RT, the target volume includes the entire visceral and parietal pleura of the lung. These structures form a circumferential envelope around the lung, extend along fissures between the lobes, and are attached to ipsilateral pericardial and diaphragmatic surfaces. Although we can use sophisticated techniques to save the dose-limiting organs, the irradiation of the circumferential envelope around the lung—even if one manages to save the underlying pulmonary parenchyma—leads to fibrosis of the thoracic cage and of the lung envelope itself with a reduction in its own elasticity. This fact reduces pulmonary excursion and oxygenation, and alters the perfusion/ventilation ratio (P/V). Thus, the oxygenated blood from the contralateral healthy lung is desaturated by the venous-arterial shunt. This is a damage functionally greater than the one provoked by pneumonectomy: the removal of both parenchyma and vascular circulation avoids this shunt effect. •Regarding RT after extrapleural pneumonectomy (EPP), EPP seems to have the advantages of removing the ipsilateral radiation dose-limiting lung, but it changes the natural history of the tumour, hindering the effectiveness of an adjuvant local treatment. Indeed, EPP halves local failures (from 63% of P/D to 31% of EPP), but, at the same time, doubles distant metastases (EPP 66% vs. P/D 35%), especially in abdominal (39% EPP vs. P/D 21%) and contralateral (22% EPP vs. P/D 11%) sites ( 3 Flores R.M. Pass H.I. Seshan V.E. et al. Extrapleural pneumonectomy versus pleurectomy/decortication in the surgical management of malignant pleural mesothelioma: Results in 663 patients. J Thorac Cardiovas Surg. 2008; 135 (e3): 620-626 Abstract Full Text Full Text PDF Scopus (463) Google Scholar ). This is probably because of the interruption of natural barriers (e.g., diaphragm) and the resulting postsurgical fluids flow (with cancer cells) into these compartments. So, although the studies with dose escalation to the hemithorax show an increasing local control (LC) (from 35% ( 4 Baldini M. Recht M. Strauss M. et al. Patterns of failure after trimodality therapy for malignant pleural mesothelioma. Ann Thorac Surg. 1997; 63: 334-338 Abstract Full Text Full Text PDF PubMed Scopus (263) Google Scholar ) to 13% ( 5 Rice D.C. Stevens C.W. Correa A.M. et al. Outcomes after extrapleural pneumonectomy and intensity-modulated radiation therapy for malignant pleural mesothelioma. Ann Thorac Surg. 2007; 84: 1685-1693 Abstract Full Text Full Text PDF PubMed Scopus (189) Google Scholar ) local failures), overall survival seems to worsen compared with P/D, even when surgery-related deaths are excluded ( 3 Flores R.M. Pass H.I. Seshan V.E. et al. Extrapleural pneumonectomy versus pleurectomy/decortication in the surgical management of malignant pleural mesothelioma: Results in 663 patients. J Thorac Cardiovas Surg. 2008; 135 (e3): 620-626 Abstract Full Text Full Text PDF Scopus (463) Google Scholar ). Volumetric Modulation Arc Radiotherapy Compared With Static Gantry Intensity-Modulated Radiotherapy for Malignant Pleural Mesothelioma Tumor: A Feasibility StudyInternational Journal of Radiation Oncology, Biology, PhysicsVol. 77Issue 3PreviewA planning study was performed to evaluate RapidArc (RA), a volumetric modulated arc technique, on malignant pleural mesothelioma. The benchmark was conventional fixed-field intensity-modulated radiotherapy (IMRT). Full-Text PDF Proton Therapy for Malignant Pleural Mesothelioma After Extrapleural PleuropneumonectomyInternational Journal of Radiation Oncology, Biology, PhysicsVol. 78Issue 2PreviewTo perform comparative planning for intensity-modulated radiotherapy (IMRT) and proton therapy (PT) for malignant pleural mesothelioma after radical surgery. Full-Text PDF In Response to Dr. Russi and ColleaguesInternational Journal of Radiation Oncology, Biology, PhysicsVol. 79Issue 4PreviewTo the Editor: Single modality therapies in the treatment of malignant pleural mesothelioma (MPM) have generally failed to prolong patient survival; as a result, multimodality treatment regimens have been developed (1). Full-Text PDF