Assessment of Visceral Pleural Invasion (VPI) in Patients with Surgically Resected Non Small Cell Lung Cancer: A Study of Interobserver Agreement.
Michal Kamionek, Ali Akalin, Karen Dresser, Armando Fraire. One Innovation Drive, Three Biotech, Worcester, MA
Background: Current standards from the IASLC and the AJCC recommend the use of elastic tissue stain for the assessment of VPI in non small cell carcinoma of lung. The value of this stain has been documented in previous studies including our own (Mod Path 2010, Vol23:405A). However, the interpretation of elastic tissue stains can be difficult. We undertook this study to determine interobserver variability in the assessment of elastic tissue stains. To this end, only tumors located 0.2 cm or less from the pleura were studied.
Design: In this study, VPI was defined as tumor invasion beyond the pleural elastic lamina as follows: PL1 tumor present beyond the elastic lamina, PL2 tumor at the pleural surface and PLX for undetermined cases. From an initial pool of 96 cases and after exclusion of cases with tumors greater than 0.2 cm from the pleura, elastic tissue stains of 69 cases initially staged as T1N0MX were submitted for independent evaluation by 3 observers. Reconciliation of discrepancies was achieved by joint review. Mean interobserver percentage agreement and the kappa statistical method were used to determine interobserver variability.
Results: Interobserver unanimity was achieved in 36 (52.2%) of the 69 cases. The percent agreement was 89.86% for PL0 (among 46 cases), 56.86% for PL1 (among 17 cases), and 33.3% for PL2 (only 1 case) and PLX (among 5 cases) categories. Total percentage agreement was 76.81%. (see bar graph below). The overall kappa value was 0.32.
Conclusions: Our study suggests that interobserver agreement of the integrity of the elastic lamina on basis of elastic stain is excellent (89.86%) in PL0 cases, but only fair at best in the remaining (PL1, PL2) categories. Our findings further suggest that while valuable, elastic tissue stains are probably best assessed by more than one observer.
Monday, February 28, 2011 2:45 PM
Platform Session: Section E, Monday Afternoon