Normal tissue tolerance to external beam radiation therapy: Lung

Radiation pneumonitis is the most common dose limiting complication of thoracic radiation. Clinically significant radiation pneumonitis usually develops in 10-20% of patients. Characteristic clinical features associated with radiation pneumonitis include dyspnea, non-productive cough, radiographic opacification confined to the outlines of the field of radiation treatment and changes in pulmonary function measures. The risk of radiation pneumonitis is related to the cumulative dose of radiation to normal tissue and to patients and tumor features. Some studies demonstrated that preexisting pulmonary lung dysfunction, tumour location in lower lobes, use of concurrent chemotherapy could increase the risk of radiation pneumonitis. Controversies persist about which dosimetric parameter optimally predicts the risk of radiation pneumonitis. Mean lung dose, V20 and V30 are the most studied parameters. However, no ideal dosimetric parameter has been identified. The objective of this review is to summarize predictive factors of radiation pneumonitis, and to evaluate the predictive ability of various dose-volume histogram parameters for routine practice. (C) 2010 Societe francaise de radiotherapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved.