Evolving techniques in the staging of lung cancer

An ideal staging system should describe the extent of a disease as precisely as possible, in order to give an optimal idea of prognosis and choice of treatment. Therefore, the most accurate techniques should be used in the best interest of the patient. In addition, a good staging system should also be based on techniques accessible to all. Current staging guidelines describe exactly the degree of tumour spread in each tumour, node, metastasis (TNM)-subset, but they do not detail how to obtain this information. Nonetheless, some differences in therapeutic outcomes between centres seem to be related to the thoroughness of pretreatment staging, e.g. the quality of the computed tomography (CT) scans, the use of positron emission tomography (PET) scans, the extent and locations of mediastinal lymph node sampling, and the accuracy of the pathological examination of resection specimens. It is not yet clear how much of the difference in outcome between centres is based on different staging strategies, resulting in stage migration (Will Rogers phenomenon), or on truly better therapeutic approaches. This report deals with these various modern techniques for lung cancer staging. The precise roles of imaging techniques such as ultrasound, CT, magnetic resonance imaging, or 18F-fluoro-2-deoxy-D-glucose PET in the assessment of the T-, N- and M-stage of the tumour are discussed in detail. Furthermore, the contribution and procedures of more invasive methods such as bronchoscopy, medical and surgical thoracoscopy, and mediastinoscopy are highlighted. A major challenge for the next revision of the lung cancer staging system will be the integration of minimal requirements for pretreatment and intra-operative staging. It will be a difficult exercise to find the best compromise between widespread applicability of the tumour, node, metastasis-system (allowing comparison between different centres and time periods) and the use of more advanced technology in the best interest of the patient