Assessing the Annual Risk of Recurrence Following Complete Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) for Diffuse Malignant Peritoneal Mesothelioma Patients

BACKGROUND: Selected diffuse malignant peritoneal mesothelioma (DMPM) patients may be radically treated with complete cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Two thirds of them recur with the possibility of iterative CRS-HIPEC and/or systemic chemotherapy. The postoperative follow-up management is based on scarce data. The recurrence profile was explored in a large national database to challenge the standard follow-up protocol.

METHODS: Consecutive, pathologically proven, epithelioid DMPM patients from the RENAPE database, treated with complete CRS-HIPEC were included in this analysis. Patients with more than 5 years of follow-up were divided into long-term control group (event-free), early relapse group (event within 2 years), and intermediate relapse group. Survival distributions were estimated by the Kaplan-Meier method.

RESULTS: Overall, 288 patients met the inclusion criteria (95% epithelioid, median PCI 18) with 197 followed-up more than 5 years, divided into long-term control (57 patients), intermediate relapse (34 patients), and early relapse (106 patients). After a median follow-up time of 71 months, the median relapse-free survival (RFS) was 37.2 months (95% confidence interval 26.4-52.8 months). The recurrence risk was highest during the first 2 years (36.8% of patients recurred) and remained around 10% per year until year 8. In the multivariate analysis, age <60 and PCI <17 were independent factors of better RFS. Interestingly, 27% of recurring patients presented distant metastases.

CONCLUSIONS: These results strengthen current follow-up guidelines, while also suggesting a close follow-up between years 5 and 8. No subgroup of patients or biomarkers have been identified to personalize follow-up.