Efficacy of a second-line treatment and prognostic factors in patients with advanced malignant peritoneal mesothelioma: a retrospective study

Abstract

Background A standard treatment for malignant peritoneal mesothelioma has not been established, and systemic chemotherapy is administered according to malignant pleural mesothelioma. We previously reported the efficacy of cisplatin plus pemetrexed as first-line chemotherapy; however, the efficacy of second-line chemotherapy remains unknown. Methods We retrospectively evaluated patients with malignant peritoneal mesothelioma who started first-line systemic chemotherapy with platinum plus pemetrexed between March 2007 and February 2019 at the National Cancer Center Hospital. Patients who received second-line chemotherapy after failure of platinum plus pemetrexed were identified. We evaluated the efficacy of first- and second-line chemotherapy, and explored the prognostic factors. Survival outcomes were determined using Kaplan-Meier estimation, and between-group differences were assessed using the log-rank test. Univariate and multivariate analyses were performed using Cox proportional hazard models. Results A total of 54 and 26 patients received platinum plus pemetrexed as first- and second-line chemotherapy, respectively (gemcitabine in 12 patients; taxane, 6; nivolumab, 3; and others, 5). In all patients, the median overall survival and progression-free survival after first-line chemotherapy were 16.6 and 7.3 months, respectively. Among patients who received second-line chemotherapy, the median overall survival, progression-free survival, and second-line overall survival were 16.9, 3.2, and 9.9 months, respectively. Patients who received 6 or more cycles of platinum plus pemetrexed as first-line chemotherapy had longer overall survival after second-line chemotherapy than those who did not (hazard ratio, 0.23; 95% confidence interval: 0.06–0.82; p = 0.02). Conclusions Second-line chemotherapy can be an option for refractory malignant peritoneal mesothelioma, especially for patients who have completed 6 cycles of platinum plus pemetrexed as a first-line chemotherapy.