Well differentiated papillary peritoneal mesothelioma treated by cytoreduction and hyperthermic intraperitoneal chemotherapy-the experience of the PSOGI registry.

Background: Well differentiated papillary peritoneal mesothelioma (WDPPM) is a rare variant of mesothelioma which affects mainly women in the reproductive age. The disease may present multifocally and recur after primary resection. Our aim was to describe the outcomes of cytoreduction (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in this disease.

Methods: Patients with histological diagnosis of WDPPM were retrieved from the PSOGI registry. Demographical and clinical data were extracted as well as outcomes data (overall survival (OS) and recurrence free survival (RFS)).

Results: We analyzed 45 patients for whom complete data was available. The majority of patients were women (n = 33, 73%) with a median age of 44 years. Preoperative chemotherapy (CT) was administered in 8 patients (18%). Median peritoneal carcinomatosis index was 9 (1-30), and complete cytoreduction was achieved in 69% of patients. There was one case (2%) of postoperative mortality, and 24% rate of severe morbidity. Overall, there were 4 deaths and 5 years OS was 80%. 8 patients (18%) had disease recurrence, all within 5 years from operation. On univariate analysis preoperative CT, high PCI and severe morbidity were associated with reduced RFS. On multivariate analysis, only preoperative CT (HR = 32.6, 95% CI: 2.39-446.2, p = 0.009) and high PCI (HR = 21.7, 95% CI: 1.11-425.7, p = 0.04) remained significant risk factors.

Conclusions: WDPPM can be a lethal disease with substantial recurrence even after aggressive treatment. Patients presenting with extensive disease or disease recurrence after surgical excision are at increased risk for relapse. CRS + HIPEC can be safely applied to WDPPM in specialized centers.