To the Editor I wish to discuss the implications of the article by Kennedy et al,1 in which the authors demonstrated the utility of intraoperative molecular imaging for the identification of nonpalpable lung tumors.1
Conventional methods of tumor localization indirectly estimate the location with markers placed near the tumor, such as computed tomography–guided lung needle marking, computed tomography–guided lipiodol marking, and virtual-assisted lung mapping.2,3 In contrast, the authors’ method is more accurate with direct localization and simple and minimally invasive without invasive procedures before surgery. It allows intuitive intraoperative procedure, while the further refined technique will allow sufficient margin even for nonpalpable lung tumors. It avoids serious complications potentially associated with puncture in conventional methods, such as air embolism and tumor dissemination,4 and adopts harmless methods for the human body such as near-infrared emission and folate analog infusion with high safety. To my knowledge, it is the most reasonable, reliable, and promising method of tumor identification to date. One point of concern is the lung cancer specificity of folate receptor alpha. With receptors simply overexpressed in lung cancer and expressed in normal lung epithelial cells,5 the tumor site may not be identified depending on the patient’s constitution and tumor variability. In fact, of 18 cases of nonpalpable lesions, 3 cases were nonidentifiable by intraoperative molecular imaging, but what do they have in common? Three benign tumors were included in this study, but are they consistent with these 3 cases? Considering importance of the versatility to deal with various cases in actual clinical practice, it is important to study further with many cases and construct a countermeasure for nonidentifiable lesions.