Lung Cancer, Histologic Stratification, and Resection Extent: Something for Surgeons to Think About

摘要

You would think that thoracic surgeons have plenty to consider when planning for a lung cancer resection in 2013. We have been bombarded with “the small nodule” less than 2 mm, which we have learned can have various inhomogeneities in its computerized tomographic (CT) analysis (1); we have to decide whether the nodule merits a lobectomy (the standard of care) or a sublobar resection (2) (for those heretics in the minority who feel that we don’t need a randomized trial to answer the sublobar vs lobectomy debate); whether we should mark the nodule preoperatively so we will be able to find it because we are sometimes trying to feel a 2-cm sponge within a giant sponge; and whether to perform the case as a video-assisted resection, a robotic resection, or (shudder) as an open procedure with rib resection/spreading. As if those deliberations were not enough, now we must start to worry about whether the (presumed lung cancer) solid or part-solid nodule presented to us on the CT scan has a critical quantifiable element of micropapillary disease, which may be associated with tumor recurrence if we do a wedge resection or a segmentectomy (which, of course, will only be the standard of care for intentional lung cancer resections if this is confirmed by the results of CALGB 140503 “A Phase III Randomized Trial of Lobectomy Versus Sublobar Resection for Small (<2 cm) Peripheral Non–Small Cell Lung Cancer” (3). The article by Nitadori et al. (4) in this issue of the Journal is a continuation of the milestone publications by the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society, which have revolutionized the pathologic classification of lung adenocarcinoma (5). As reviewed by Suh (6), the new classification eliminates the categories of bronchioloalveolar carcinoma and mixed subtype adenocarcinoma to achieve precise correlations between predominant histologic subtypes of lung adenocarcinoma and survival in surgically resected patients. The Nitadori et al. article (4) retrospectively analyzed 476 lobectomies and 258 limited resections (either by wedge resection or anatomic segmentectomy) at a single institution in patients with lung adenocarcinomas of 2 cm or less. An important validation of the prognostic importance of the new classification system was demonstrated in the patients who had lobectomies for these small tumors; however, this was not seen in the limited resection group. Why is this? Is it because of the heterogeneity of the procedures performed? Is it because of the absence of clear-cut large margins? There are some other intriguing aspects of the limited resection group in these patients that also should be mentioned. The authors specify that the limited resection group is a combination of compromised (77.1%) patients and patients having intentional resection by less than a lobectomy (22.9%). The literature has documented that wedge resections performed in this population have a substantially higher incidence of local recurrence (7,8); yet, in this series the wedge resections (which were 2.6-fold more frequent than segmentectomies) did not reach statistical significance with regard to the cumulative incidence of recurrences compared with segmentectomies. One could speculate that this lack of recurrences in the wedge resection group was because of larger than average margins taken at the time of resection; however, another interesting finding in this series is that the size of the margin in the sublobar resection group did not influence the cumulative incidence of recurrence. This lack of margin size influence is also disturbingly different from publications com