Selection and delineation of lymph node target volume for lung cancer conformal radiotherapy. Proposal for standardizing terminology based on surgical experience.

Abstract

To select and delineate the target volumes for definitive or postoperative radiotherapy for lung cancer. The lymphatics of the lung and the dissemination of tumor cells to the intra- and extrathoracic lymph nodes are described. The incidence of involvement of the different lymph node sites in the chest is analyzed. The involvement of the contralateral hilar and/or supraclavicular lymph nodes and the consequences for target volume selection for curative radiotherapy are discussed. CT-based nodal classification and distribution of lymph nodes in the chest in CT-axial slices are presented. The sentinel node concept (SNC) and the preliminary data available for lung cancer are described. A critical review of the current TNM classification for lung cancer and the implications for target volume selection is given. The individual target volume selection and delineation have to be based on clinical and pathological data from large surgical. studies and upon the individual pathological and diagnostic patient data. The selection and delineation of the clinical target volumes for definitive and for postoperative radiotherapy, dependent on the lymph node involvement, are presented. Criteria for the selection and delineation of the clinical target volumes for definitive and for postoperative conformal radiotherapy in axial CT slices under consideration of site, size and stage of the lung cancer are described. Recommendations for target volume selection for definitive or postoperative radiotherapy are presented.