The association between pleural fluid exposure and survival in malignant pleural mesothelioma: a retrospective cohort study in 761 patients

Malignant pleural mesothelioma(MPM) presents with malignant pleural effusion(MPE) in most patients. There is pre-clinical evidence that MPE may not be a simple bystander of malignancy,but potentially has biological properties increasing cancer cell proliferation.If this is the case,management of MPE may need to shift from current symptomatic strategies to aggressive fluid removal to impact on survival. Aim: to analyse the association of pleural fluid exposure(duration of effusion,& pleurodesis success)with survival in MPM. Method:Data on 761 patients diagnosed with MPM between 2008-2018 was collected from patients’ medical records in 3 UK pleural units.The medical images were reviewed for presence,size & duration of pleural effusion in order to analyse pleural fluid exposure(total number of days pleural effusion was present overall) & pleurodesis effects. Results: The median overall survival was 278 days(IQR 378).Median survival: 473,378,258 days (p 0.0006) with complete, partial,& no pleurodesis respectively.With time-dependent analysis,pleurodesis success remained a significant influencing factor on survival (p 0.002). There was no association between pleural fluid exposure time & survival (p 0.2) with time-dependent covariate analysis(model included serum albumin,MPM subtype,performance status,presence of symptoms at diagnosis,chemotherapy received). Conclusion: Pleurodesis success is associated with improved survival,however given the limitations of this retrospective study,it is unclear whether duration of MPM exposure to pleural fluid correlates with survival.Future prospective studies are required to assess this potentially important mechanism.