Analysis of survival of patients with metastatic malignant pleural mesothelioma

Aim: To report the outcomes and prognosis of patients with malignant pleural mesothelioma (MPM) who present with or develop metastases during treatment. Methods: This is a retrospective observational study of patients diagnosed with MPM over 7 years. Metastases at presentation or during follow-up were recorded. Multivariate Cox regression was used to evaluate the relationship of clinicopathologic variables and overall survival (OS). Logistic regression was used for propensity score matching of patients to assess chemotherapy treatment effect. Results: There were 367 patients included with a median age of 71 years (range, 29-91). A total of 69 patients (18%) had metastases: 14 at presentation and 55 during follow-up. Patients presenting with metastases had significantly worse median and 2-year OS compared to those developing metastases during follow-up: 13.3 months (95% confidence interval [CI], 2-24.6 months) and 0% versus 20.2 months (95% CI, 16.7-23.3 months) and 33%, respectively (p = 0.029). Female sex, age >70 years, nonepithelioid histology, and not receiving chemotherapy were independent poor prognostic factors. There was no difference in OS of patients with locally advanced (T4) disease compared to metastatic disease (M1): median OS 10.7 months (95% CI, 5.9-15.6) versus 13.3 months (95% CI, 2-24.6) (p = 0.18), respectively. Following propensity matching, sarcomatoid histology (hazard ratio, 7.86 [95% CI, 3.64-16.95]; p < 0.001) and multiple lines of chemotherapy (hazard ratio, 0.38 [95% CI, 0.19-0.84]; p = 0.015) were significant independent prognostic factors for OS. Conclusions: T4 disease carries a similar OS as metastatic MPM. Female sex, advanced age, nonepithelioid histology, and not receiving chemotherapy were independent poor prognostic factors.