摘要:AbstractIn this study, the authors aim to examine the root causes of the delays in reaching a definitive diagnosis of lung cancer in time and investigate to reduce it by Six Sigma Methodology. The SIPOC table, Fishbone diagram and FMEA table are generated. Thirteen types of causes are identified. They cause patients with lung disease to enter the Stage IIIB and Stage IV. It is concluded that absence of patient's check-up habit and patient's anxiety and worry that cause late admission to doctor are the crucial causes of delays that may lead to inoperability.