The clinical outcome of non-small cell lung cancer patients with adjacent lobe invasion: The optimal classification according to the status of the interlobar pleura at the invasion point

OBJECTIVES: The aim of this study was to analyse the survival of non-small cell lung cancer (NSCLC) patients with adjacent lobe invasion (ALI) with emphasis on the interlobar fissure status at the tumour invasion point. METHODS: We retrospectively evaluated 2097 consecutive patients with surgically resected NSCLC from July 1993 through April 2006. Of these, 90 (4.3%) patients had tumours with ALI. We divided ALIs into two types by histological examination using elastic stains: direct ALI beyond the incomplete fissure (ALI-D, n = 18) and ALI across the interlobar fissure (ALI-A, n = 72), and compared the clinicopathological features and survival. RESULTS: The patients with ALI demonstrated an intermediate survival between T2a and T2b tumours (5-year overall survival: T2a, 61.0%; ALI, 59.6%; T2b, 49.2%). There were distinct survival differences between the patients with ALI-A and ALI-D (5-year overall survival: ALI-D, 85.7%; ALI-A, 52.0%; P = 0.010). The survival of patients with ALI-A was not statistically different from that of patients with T2b tumours, regardless of the tumour size (P = 0.846). The survival of the patients with ALI-D did not statistically differ from those with T1a or T1b tumours (P = 0.765 and 0.418, respectively). CONCLUSIONS: Our results indicate that the interlobar fissure status affects the survival of the patients with ALI. ALI should be examined by elastic stains and only ALI-A should be classified as true ALI. We propose that ALI-A tumours with a size of ≤5 cm should be assigned to T2b, but ALI-D tumours do not require an adjustment of the T descriptor.