The Association Between Pleural Fluid Exposure and Survival in Pleural Mesothelioma

Background Most patients with malignant pleural mesothelioma (MPM) seek treatment with malignant pleural effusion (MPE). In vitro evidence suggests that MPE may not be a simple bystander of malignancy, but rather potentially has biological properties that improve cancer cell survival and promote cancer progression. If this is the case, MPE management may need to shift from current symptomatic strategies to aggressive fluid removal to impact survival. Research Question Is there an association between pleural fluid exposure and survival in MPM? Study Design and Methods Data from 761 patients who received a diagnosis of MPM between 2008 and 2018 were collected from patient medical records in three UK pleural units. Data included factors previously identified as influencing prognosis in MPM. Medical imaging was reviewed for presence, size, and duration of pleural effusion. Time-dependent covariate analysis of pleural fluid exposure and survival (model included weight loss, serum albumin, hemoglobin, MPM subtype, performance status, chemotherapy, and age) and multivariate Cox regression analysis of pleurodesis and survival were conducted. Results Median overall survival was 278 days (interquartile range, 127-505 days; 95% CI, 253-301 days). Pleural fluid exposure duration showed no association with survival (hazard ratio, 1.0; 95% CI, 1.0-1.0). Median survival was 473, 378, and 258 days with complete, partial, and no pleurodesis (P = .008). Interpretation Pleurodesis success seems to be associated with improved survival; however, it is unclear whether duration of MPM exposure to pleural fluid is associated with survival within the limitations of this retrospective study. Future prospective studies are required to assess this potentially important mechanism.