The American Society of Clinical Oncology (ASCO) previously published evidencebased guidelines for the treatment of unresectable non–small-cell lung cancer (NSCLC) [1]. ASCO guidelines are updated periodically by the responsible Expert Panel (Appendix) [2]. For the 2003 update, a methodology similar to that applied in the original ASCO practice guidelines for treatment of unresectable NSCLC was used. Pertinent information published from 1996 through March 2003 was reviewed. The MEDLINE database (1996 through October 2002; National Library of Medicine, Bethesda, MD) was searched to identify relevant information from the published literature for this update. A series of searches was conducted using the medical subject headings, “carcinoma, non–small-cell lung,” “diagnostic imaging,” “neoplasm staging,” “mediastinoscopy,” “bone neoplasms,” “brain neoplasms,” “liver neoplasms,” “adrenal gland neoplasms,” “non–small-cell lung cancer,” “radionuclide imaging,” “bisphosphonates,” “radiotherapy,” “smoking,” “chemoprevention,” and the text words “chemotherapy,” “bone scan,” “PET,” and “zoledronic acid.” These terms were combined with the study design–related subject headings or text words “meta-analysis” and “randomized controlled trial.” Search results were limited to human studies and English-language articles. The Cochrane Library was searched in October 2002 using the phrase “lung cancer.” Directed searches based on the bibliographies of primary articles were also performed. Randomized trials published in the literature since October 2002, as well as data presented at ASCO Annual Meetings, were added to the evidence for these guidelines at the discretion of members of the Expert Panel. The entire update committee met once to discuss strategy and assign responsibilities for the update. A writing committee subsequently met to further review the literature searches, collate different sections of the update, and refine the manuscript. A draft update was circulated to the full Expert Panel for review and approval. The final document was also reviewed by ASCO’s Health Services Research Committee and the ASCO Board of Directors. Each recommendation from the 1997 guideline is listed below, and is followed by an updated (2003) recommendation, if applicable. “No change” is indicated if a particular recommendation has not been revised. A summary of the evidence follows thereafter. In order to preserve the framework of the 1997 guideline, information and recommendations regarding major topics, such as fluorodeoxyglucose positron emission tomography (FDGPET), have been divided and distributed to the appropriate section of the text. ASCO considers adherence to these guidelines to be voluntary. The ultimate determination regarding their application is to be made by the physician in light of each From the American Society of Clinical Oncology, Alexandria, VA.