New reference equations for lung function can affect eligibility for lung cancer surgery.

<bold>Background:</bold> The standard treatment for early-stage non-small cell lung cancer is surgery. The current guidelines on pre-operative lung function assessment are based on the former European Coal and Steel Community (ECSC) reference equations. The Global Lung Initiative (GLI) and Danish Lung Function Material (DALFUMAT) have published new reference equations for calculating predicted forced expiratory volume in the first second (FEV1) and lung carbon monoxide diffusing capacity, (DLCO). If the values of the predicted FEV1 or DLCO are below 40% another treatment approach than surgery should be considered. <bold>Objective:</bold> This study has assessed whether the new reference equations would have affected the pre-operative assessment of patients treated for lung cancer. <bold>Methods:</bold> Data was collected from 1400 patients’ records. The percent of predicted values using the ECSC reference equations was compared to the percent of predicted values using the GLI and DALFUMAT reference equations. <bold>Results:</bold> The use of the GLI reference equations did not make a significant change in number of patients with FEV1 or DLCO below 40%. The use of DALFUMAT reference equations made a significant change in the number of patients who had a FEV1 below 40% and number of females with DLCO below 40%. <bold>Conclusion:</bold> The use of other reference equations could affect the clinical assessment of patients treated for lung cancer.