The Impact of Pleural Invasion and Its Subdivision on T Staging of Non-Small Cell Lung Cancer.
Kareem Aboualfa, Eric Lim, Peter Goldstraw, Michael Dusmet, George Ladas, Simon Jordan, Andrew G Nicholson. Royal Brompton and Harefield NHS Foundation Trust, London, United Kingdom; Imperial College, London, United Kingdom
Background: Visceral pleural invasion (VPI) is a factor that upstages T1 tumours to T2 in the 7th TNM for non-small cell lung carcinoma (NSCLC). However. the value of further subdivision of VPI is controversial. This study assesses the significance of VPI on survival and the value of splitting pleural invasion into further subgroups.
Design: Histopathological data was prospectively collected on 728 resected NSCLCs between 1999 and 2006, according to the RCPathology Minimum Data Set, of which 465 had overall survival data (OS) and 455 had disease free survival data (DFS). Pleural invasion was assessed by using haematoxylin and eosin (H&E) staining and Elastin van Gieson (EVG) staining to highlight the pleura. Pleural invasion was further subclassified according to proposed criteria for PL0 (no VPI), PL1 (VPI not reaching the surface), PL2 (VPI reaching the surface), PL3. (parietal pleural invasion). To assess VPI as an independent variable, T category based purely on size was also documented without contribution of VPI. Actuarial survival was estimated using the Kaplan-Meier method and compared using the Log-rank test. Cox proportional hazards regression was used to ascertain the individual contribution of factors associated with survival and to compare adjusted survival between the groups.
Results: The presence of visceral pleural invasion was associated with a hazard ratio of 1.57 (95%CI 1.19 to 2.11; P=0.001) and 1.49 (1.11 to 2.01; P=0.007), adding 56% and 49% to the mortality at each stage, for the 6th and 7th edition of the TNM respectively, in relation to OS. There was no evidence to suggest any difference in overall (P=0.262) or disease free survival (P=0.183) between the PL1-3 categories.
Conclusions: We confirm the importance of tumour breaching the outer elastin layer of the visceral pleura (VPI) as a signifcant factor in T staging, independent of tumour size. However our data do not support further subdivision of pleural invasion into PL1-3 subcategories.
Monday, February 28, 2011 2:30 PM
Platform Session: Section E, Monday Afternoon