Asbestos Bodies in Lung Tissue Are Associated with Survival Duration for Epithelial, but Not Non-Epithelial, Mesothelioma in Patients Undergoing Extrapleural Pneumonectomy
JJ Godleski, WG Richards, M Katler, J Mueller, DJ Sugarbaker. Brigham and Women's Hospital, Boston, MA
Background: Prior reports which have inconsistently linked asbestos exposure to outcome in malignant pleural mesothelioma (MPM) have often been under-powered to stratify for histological subtype or type of therapy. We analyzed patient survival in relation to asbestos body (AB) counts obtained in lung tissue from MPM patients treated with extrapleural pneumonectomy (EPP), stratifying by histology.
Design: Lung tissue for AB analysis was collected as part of the pathologic assessment of EPP specimens and reported in the clinical record. Clorox digestion was carried out by standard methods and counts made using phase contrast light microscopy. The logrank statistic was used to compare Kaplan-Meier estimates of overall survival from diagnosis for patients grouped by AB count within epithelial and non-epithelial histological subgroups defined by WHO criteria.
Results: 559 patients were treated with EPP between 1988 and 2005. Of these 365 had tumors with epithelial histology and 194 had non-epithelial tumors. Among epithelial cases, (72% male, median age 57) 234 (64%) had AB counts prospectively determined compared to 142 (73%) non-epithelial cases (90% male, median age 60). Median AB counts were 265 per gram wet weight for epithelial compared to 1084 per gram for non-epithelials. Median control AB count for our laboratory is 20 per gram. Among patients with epithelial MPM, 105 patients with AB counts <200/gm had a 27-month median survival, compared to 17.1 months for 129 patients with >200/gm (p=0.0003). By contrast, median survival of patients with non-epithelial MPM did not differ between the 32 patients with <200/gm (9.5 months) and the 109 patients with >200/gm (12.7 months; p=0.58). A similar pattern of results was obtained by dichotomizing AB count at 100, 300, 500 or 1000/gm.
Conclusions: Patients with epithelial MPM have lower lung asbestos fiber AB burden than those with non-epithelial MPM. Smaller AB counts were associated with longer survival among patients with epithelial tumors, but AB burden was unrelated to survival among those with non-epithelial MPM. These results suggest that AB counts have prognostic significance and support the view that apart from the defining histological differences, epithelial and non-epithelial MPM represent disease entities with distinct biology, clinical behavior, and response to therapy.
Monday, March 9, 2009 1:00 PM
Poster Session II # 218, Monday Afternoon