In Reply We thank Köylü and Güven for their critique of our recently published article that examined the association of visceral pleural invasion (VPI) with recurrence and survival in patients with peripheral clinically node-negative non–small cell lung cancer 2 cm or smaller in size who were randomized to lobar or sublobar resection in the CALGB 140503 study. Our results showed that, even in this highly selected cohort, VPI was associated with higher rates of lung cancer recurrence and worse disease-free survival (DFS). To our knowledge, these results represent the only data derived from a prospective randomized clinical trial where mandatory tracking of disease recurrence was an essential component of the primary end point. Importantly, we also showed that the negative impact of VPI on recurrence and DFS was independent of the extent of pulmonary resection. However, we re-emphasize that our conclusions should be tempered by the unplanned exploratory nature of the analysis, especially because the trial was not powered to detect differences in survival based on VPI. Köylü and Güven are appropriately concerned that these results may be confounded by pathologic variables not examined in our analysis, such as lymphovascular invasion, adenocarcinoma subtype, or the controversial spread through the air spaces. A similar concern was also expressed by the Editorial that accompanied the article. We agree that these are legitimate concerns. Unfortunately, the trial protocol did not mandate a central pathology review, a gargantuan logistical challenge for an international trial where patient accrual extended over a decade. In addition, these variables were either not appreciated or were not considered prognostically relevant at the time of initiation of the trial in 2005. To our knowledge, these variables have yet to be validated as predictors of worse oncologic outcomes in a prospective controlled setting. Nonetheless, the Alliance of Clinical Trials in Oncology recently activated A152429, a correlative study that will address this important limitation. The study will examine the impact of these histologic variables on outcomes in CALGB 140503. The study represents an important collaboration between the International Association for the Study of Lung Cancer and the Alliance. In this study, we will retrieve histopathology slides of the index resections from 7 of the highest accruing centers. The deidentified slides will be scanned and loaded on a common server for review by a blinded pathology committee whose findings will be subsequently correlated with recurrence and survival. Although this might prove to be another logistical challenge, the study, once completed, will add clinically meaningful information to the existing body of literature.