N2 involvement in lung cancer: the Danaïdes' barrel.

In the article ‘Time to refine N2 staging’ [1], Matsunaga et al. investigated the relationship between the prognosis and the location of the primary tumour and nodes (LN) involved. They suggested a classification of these patients to either cN2α, which consisted of an upper lobe tumour with clinical positive ipsilateral upper mediastinal LNs (station: 2R and 4R on the right and 2L, 4L, 5 and 6 on the left), or cN2β, which was a lower lobe tumour with clinical positive ipsilateral mediastinal LNs (station: 7, 8 and 9 on both sides) [1]. They found that survival was better in the cN2α group regardless of the number of LN stations involved. The following points need to be considered: