Defining N2 disease in non-small cell lung cancer

In summary, patients with N2 disease constitute a heterogeneous population with differing treatments and prognoses. Subtleties in the presentation, method of diagnosis, extent of nodal involvement, and patterns of nodal involvement must be taken into consideration to determine prognosis and optimal therapy. Is the patient with an incidental, pathologically identified, single focus of mediastinal disease the same as the patient with clinically identified multilevel bulky unresectable disease? Clearly not, although both patients share a similar stage, grouping the data presented here clearly demonstrate that these patients differ considerable in their prognosis and in their treatment. The current staging system attempts at assigning a single unifying definition of N2 fails to take into account the numerous subtleties inherent in this patient population. Although it is unlikely that N2 disease will be subclassified to any significant extent, some of these factors may eventually find themselves into a modern revision of our current staging system. For now, the upcoming IASLC revisions to the Union Internationale Contre le Cancer (UICC) staging system will not alter the definitions of nodal disease or add distinct subsets. Therefore, it is imperative that physicians evaluating and treating patients with N2 disease recognize and appreciate the influence of these subtle differences in presentation. Decision making surrounding the treatment of N2-positive patients will continue to remain complex as long as the definition of the disease remains heterogeneous.