Clinical-pathological Characteristics and Prognostic Factors for Malignant Peritoneal Mesothelioma in the Elderly

Background: Malignant peritoneal mesothelioma (MPM) is a rare disease characterized by atypical symptoms, difficult diagnosis, variable course and poor prognosis, and it develops mainly in the elderly. The authors aimed to identify the clinical-pathological characteristics, prognosis, and prognostic factors in the elderly MPM patients.Methods: From the National Cancer Institute Surveillance Epidemiology End Results (SEER) database, 1492 patients with MPM from 1975 to 2016 were selected and divided into the elderly group (≥65) and the adult group (<65). We compared the clinical-pathological characteristics and treatment methods of elderly group (N=665) and adult group (N=827). At the same time, we analyzed specific selected clinical-pathological parameters and prognostic factors for the elderly MPM patients.Results: Compared with the adult group, the elderly group had a higher percentage of male patients (P = 0.017), white patients (P = 0.043), a lower proportion of insured patients (P < 0.001), married patients (P < 0.001), patients with peritoneal tumors (P = 0.006), patients who underwent surgery (P < 0.001), and chemotherapy (P < 0.001). There was a significant difference in the differentiation grade between the two groups (P = 0.003). The elderly patients had a shorter median survival time compared with the adult patients (6 months vs 19 months). Uninsured (hazard ratio (HR): 5.187, P = 0.005), sarcomatoid type (HR: 3.913, P <0.001), poorly differentiated (HR: 3.900, P < 0.001), distant metastasis (HR: 1.735, P = 0.001), no cancer-directed surgery (HR: 1.733, P < 0.001), and no chemotherapy (HR: 1.532, P < 0.001) were independently associated with poorer prognosis of elderly MPM patients.Conclusion: Compared with the adult patients, elderly MPM patients had higher male ratio, poor differentiation and relatively conservative treatment. The cancer-specific survival (CSS) rate of elderly MPM patients was significantly lower than that of adult patients. Insurance status, histology type, differentiation grade, stage, surgery status, and chemotherapy status were all independent prognostic factors for elderly MPM patients.