Radical surgery in malignnant pleural mesothelioma (MPM): An analysis of SEER database.

8554 Background: MPM is an aggressive malignnancy with poor overall prognosis. A combined treatment approach involving radical surgery (RS), radiation (RT) and chemotherapy (CT) provide improved survival compared to systemic treatment alone. Selecting patients who may benefit from RS is challenging. The NCCN guidelines recommend that up to T3N1M0 (Stage IIIA) epithelioid or biphasic MPM should be considered for multimodality therapy incorporating RS. However, the impact of clinical and pathologic features within each histologic subtype of MPM on RS outcomes is unknown. Methods: MPM patients from the SEER 18 program from 2004-2015 were identified. Cox proportional hazard regression models were used to examine the independent contribution of several clinical and pathologic features on overall survival (OS) in patients who received RS vs those that did not. Results: A total of 5,498 MPM patients were identified, of which 531 underwent RS. Overall, RS was associated with improved OS in the multivariate model adjusting for important clinical and pathological characteristics (Table). When stratifying according to histology, epithelioid subtype was linked to improved OS with RS despite of the presence male gender, age > 60 years old, T3, T4 or N2 or above disease; and the OS improved among those who also underwent CT ± RT with RS. Patients with sarcomatoid histology also had OS benefit from RS (HR=0.59, 95%CI: 0.37-0.93), even those that were > 60 years old, but not among those with more advanced disease (T3/4, N2/3). Sarcomatoid patients who received CT ± RT (HR = 0.52, 95%CI: 0.30-0.90) also experienced OS benefit. Among biphasic histology, no OS benefit was found overall (P = 0.11) or within other high-risk clinical features except for those who were treated CT ± RT (HR = 0.64, 95%CI: 0.45-0.90). Conclusions: Our findings demonstrate that the presence of high-risk clinical and pathologic features does not impact OS benefit of RS in epithelioid MPM, however should be considered when deciding on RS in sarcomatoid and biphasic histologies. Poor prognostic histology especially sarcomatoid subtype may experience improved survival with RS if in conjunction with other treatment modalities.[Table: see text]