Asbestos Bodies In Lung Tissue Are Associated With Pathologic Features And Patient Outcome For Epithelial But Not Non-Epithelial Mesothelioma Treated By Extrapleural Pneumonectomy

We examined patient survival and pathologic tumor features in relation to asbestos body (AB) counts in lung tissue from patients with malignant pleural mesothelioma (MPM). Lung tissue was digested with Clorox® by standard methods. AB counts were made using phase contrast light microscopy. Kaplan‐Meier estimates of overall survival were compared using logrank tests for dichotomized AB count in WHO epithelial (E) and non‐epithelial (NE) MPM subgroups. Association of AB count with reported pathological features was assessed using Fisher's Exact test. From 1988 to 2005, 365 E (72% male; median age 57) and 194 NE patients (90% male; median age 60) were treated. Of these, 234 (64%) E and 142 (73%) NE had AB evaluation. Median AB count for E was 265/g (wet weight) vs. 1084/g for NE and 20/g control AB count. Among E patients, 105 with AB≤200/g had 27‐mo. median survial vs 17.1 mo. for 129 with >200 AB/g (p=0.0003). By contrast, survival for 32 NE with AB≤200/g (9.5 mo.) did not differ from 109 NE with >200 AB/g (12.7 mo.;p=0.58). AB counts above median were significantly associated with involvement of lung parenchema (p=0.0055) and intralobar fissure (p=0.0176) for E but not NE. No relation of AB to diaphragm, pericardium or chest wall involvement was evident. We conclude that AB has prognostic significance in MPM and that E and NE represent distinct disease entities. Supported by the International Mesothelioma Program