PET/CT in Pleural Mesothelioma after Talc Pleurodesis and Induction Chemotherapy: Histologic Findings at Hot and Cold Spots.
Alex Soltermann, Peter Kestenholz, Holger Moch, Walter Weder, Hans Steinert. University Hospital Zurich, Switzerland
Background: The role of computed tomography-positron emission tomography with [18F]-fluoro-deoxy-D-glucose (FDG-PET/CT) in evaluating the effect of induction chemotherapy in malignant pleural mesothelioma (MPM) is unknown. FDG uptake may vary at different sites due to tissue heterogeneity. We aimed for comparing histologic findings at tumor sites with high versus low FDG uptake.
Design: 20 MPM patients with talc pleurodesis during diagnostic thoracoscopy and induction chemotherapy followed by extrapleural pleuro-pneumonectomy (EPP) were included. All patients received a FDG PET/CT scan prior to surgery. Orthogonal whole sections (n total = 86) were taken at areas of maximum (SUVmax, n = 53) and of no FDG uptake (n = 33) and assessed for several histologic parameters (in mm, percentage or semi-quantitatively 0-3) using dichotomized data and Chi-squared tests.
Results: Overall median SUVmax was 2.20 (p<0.001 for hot/cold spots correlated with SUVmax). Hot spots were significantly associated with increased thickness of total pleural rind (p=0.046) and fibrosis (p=0.023) but not thickness of tumor or giant cell reaction. No relation was found with percent sarcomatoid histotype, tumor amount, tumor density, tumor viability and peritumoral chronic inflammation, apart a trend for higher vessel density (p=0.088). Further, hot spots were significantly associated with high proliferation rate Mib-1 of tumor (p=0.044) but not of giant cells. No relation was found for maximal Glut-1 expression intensity in either tumor or giant cells.
Conclusions: Interpretation of PET/CT data in MPM is difficult after talc pleurodesis and induction chemotherapy due to complex tissue composition which particularly includes a mixture of tumor and giant cells, both positive for Glut-1. Most consistently, hot spots are localized to pleural rind areas with high fibrotic activity.
Tuesday, March 1, 2011 9:30 AM
Poster Session III # 284, Tuesday Morning