The staging of lung cancer

Staging is one of the most important components in the management of lung cancer. Accurate staging is important because it allows the clinician to predict prognosis and assign appropriate therapy and also provides a system that allows clinicians and researchers to stratify patients into reasonably homogenous groups so that treatment outcomes can be appropriately compared. Tumor staging is broadly broken down into clinical staging and pathologic staging. Clinical stage refers to the best prediction of lung cancer stage prior to the commencement of therapy. Pathologic stage refers to the best prediction of stage following pathologic analysis of the patient's tumor, lymph nodes, and/or metastases and is usually applied following surgical resection or exploration. The distinction between clinical and pathologic stage becomes slightly less clear, however, when patients undergo some form of histologic staging without surgical resection or exploration. Thus, a patient may undergo histologic assessment of mediastinal nodes by endobronchial ultrasound (EBUS) fi ne-needle aspiration (FNA) prior to surgical resection. The information thus gained is considered to contribute to the clinical not pathologic stage, which would be determined by the pathologic fi ndings at surgery. If the same patient was found to have ipsilateral lymph node metastases at EBUS and then went on to receive nonsurgical therapy, he would be considered to have pathologic stage N2 (p-stage IIIa) disease. Ultimately, pathologic stage is determined by the highest level histologic evidence that is available. Following preoperative therapy (such as chemotherapy and radiation), subsequent pathologic staging is associated with the pre fi x “y”. Thus a patient with ipsilateral nodal metastases might be downstaged by preoperative chemotherapy from pN2 prior to treatment to ypN0 after pathologic analysis of the post-chemotherapy surgical specimen.