Introduction
These revised recommendations for incidentally discovered lung nodules incorporate several changes from the original Fleischner Society guidelines for management of solid or subsolid nodules (1,2). The purpose of these recommendations is to reduce the number of unnecessary follow-up examinations while providing greater discretion to the radiologist, clinician, and patient to make management decisions. Thus, a range of times rather than a specific interval for follow-up computed tomography (CT) is given for many scenarios. This change has been made in recognition of the multiple factors that determine risk and that cannot be easily incorporated into a summary table, as well as the important role of patient preference for either more aggressive or more conservative management. Although we have taken into account new data from the National Lung Screening Trial (NLST), Nederlans-Leuvens Longkanker Screenings Onderzoek (NELSON), International Early Lung Cancer Action Program (iELCAP), Pan-Canadian Early Detection of Lung Cancer Study (PanCan), and British Columbia Cancer Agency (BCCA) cancer screening trials, all of which support the use of less aggressive management of small nodules, we recognize that screening programs have defined protocols to educate candidates about potential risks and the need for consistent monitoring, whereas incidentally identified nodules represent a separate population that requires a more varied approach to clinical management (3–7).
These recommendations refer to incidentally encountered lung nodules detected at CT in adult patients who are at least 35 years old. Separate guidelines have been issued for lung cancer screening, such as those from the American College of Radiology (ACR), and we support the use of those guidelines when interpreting the results of CT screening (8). Specific recommendations are provided for patients with multiple solid and subsolid nodules, and several other commonly encountered clinical situations are addressed.
These guidelines are not intended for use in patients with known primary cancers who are at risk for metastases, nor are they intended for use in immunocompromised patients who are at risk for infection; in these patients, treatment should be based on the specific clinical situation. Also, because lung cancer is rare in children and adults younger than 35 years, these guidelines are not appropriate for such patients. When incidental nodules are encountered in young patients, management decisions should be made on a case-by-case basis, and the physician should recognize that infectious causes are more likely than cancer and that use of serial CT should be minimized. Most nodules smaller than 1 cm will not be visible on chest radiographs; however, for larger solid nodules that are clearly visualized and are considered low risk, follow-up with radiography rather than CT may be appropriate to take advantage of the lower cost and lower radiation exposure.