Prognostic Factors of Long-Term Survival and Conditional Survival Analysis in MPM Patients Treated with CRS+HIPEC: A Retrospective Study of Two Centers.

Objectives: This study was designed to explore the survival benefit factors of malignant peritoneal mesothelioma (MPM) patients after cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) and to make dynamic survival prediction by conditional survival (CS).

Methods: Data of 212 patients with MPM who underwent CRS+HIPEC were retrospectively analyzed. Patients were divided into long-term survival (LTS) group (≥48.0 months) and short-term survival (STS) group (≤16.0 months) according to OS. Conditional survival is the probability of surviving y years after already survived for x years. Univariate and multivariate analyses were performed to explore the favorable factors of LTS. Conditional survival and Kaplan-Meier were applied to assess the postoperative survival probability.

Results: Ninety patients were enrolled: 53 (58.9%) were LTS, and 37 (41.1%) were STS. Univariate analysis revealed 14 meaningful factors (P < 0.05): age, surgery history, Karnofsky performance status, pathological types, tumor vascular emboli, lymphatic metastasis, Ki-67 index, preoperative CA125 level, peritoneal cancer index (PCI), completeness of cytoreduction, bleeding, red blood cell (RBC) transfusion, ascites, and severe adverse events (SAEs). Multivariate analysis identified that PCI ≤ 20, less RBC transfusion and no SAEs were independent prognostic factors for LTS. Five-year CS increased from 27% at 0 years to 84% at 4 years with the increasing number of survival years. The survival curve flattens at postoperative 5 years.

Conclusions: The key factors in CRS+HIPEC for MPM patients to achieve LTS are lower tumor burden, less intraoperative RBC transfusion, and prevention of SAEs. Malignant peritoneal mesothelioma patients demonstrated a substantial increase in CS over time. Some patients may achieve clinical cure 5 years after surgery.