P3.03-037 Impact of Sarcomatoid Component in Patients with Biphasic Mesothelioma: Review of 118 Patients: Topic: Mesothelioma Clinical

Abstract

Biphasic mesothelioma has a poor prognosis. There is no clear evidence on the role of multimodality treatment in patients with biphasic mesothelioma. The aim of this study was to analyze the impact of pathological features on survival, to determine which patients may benefit from multimodality treatment. Between January 2005 and December 2015, 214 patients with biopsy-proven biphasic mesothelioma were retrospectively identified to fulfil our inclusion criteria. The primary outcome was survival measured from time of diagnosis. Two slides were reviewed for each patient by a specialist thoracic pathologist. Slides were stained with Hematoxylin and Eosin (H+E) and the immunohistochemically-stained slides were digitally scanned and analyzed using a Hamamatsu Nanozoomer scanner (Hamamatsu ‘NDP.View2’). The proportion of epithelioid and sarcomatoid components on each slide was mapped and its area in mm2 recorded as a percentage of the total tumor area studied. Necrosis and lymphovascular invasion were analyzed. Patients with no slides available were excluded from the analysis (n=96). All eligible patients (n=118) were followed up until May 2016. One hundred and eighteen patients were included in the analysis, 106 (89.9%) were male with a median age of 73 (range 53 - 91). Twenty-eight patients (23.7%) underwent Pleurectomy Decortication (PD) and 90 patients received medical treatment alone, either with chemotherapy or best supportive care. The median overall survival (OS) was 11.2 months (range 0.3 – 36.2). At 1 year and 2 years, 49.1% and 6.4% of patients were alive respectively. Uni-variable analysis revealed both age and PD to be associated with improved survival (p=0.004 and p=0.004). Patients treated with PD had OS of 12.8 months (range 5.6 - 36), compared to 9.2 months (range 0.3 – 31.8) in patients receiving medical treatment alone. No lymphovascular invasion was identified in any specimen. Necrosis was not correlated with survival (p=0.76). The proportion of epithelioid (p=0.45) or sarcomatoid (p=0.60) component within the specimen did not correlate significantly with overall survival. This remained true when patients undergoing surgical PD (epitheloid p=0.42 and sarcomatoid p=0.60) and medical treatment (epitheloid p=0.43 and sarcomatoid p=0.11) were analyzed as separate subgroups. The prognosis for patients with biphasic mesothelioma remains poor, even after multimodality treatment including pleurectomy decortication (PD). However, necrosis and the proportion of sarcomatoid histology is not helpful in selecting patients with more favorable prognosis, who may benefit from a multimodality approach.