Pseudomyxoma Peritonei: Clinical Pathological and Biological Prognostic Factors in Patients Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (HIPEC)
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Surgical cytoreduction combined with hyperthermic intraperitoneal chemotherapy (HIPEC) has been recently advocated as the standard of care for pseudomyxoma peritonei (PMP). We reviewed our 10-year monoinstitutional case series to identify selection factors predicting postoperative outcome.
One hundred and four patients with PMP were operated on with the aim of performing adequate cytoreduction (residual tumor nodules ≤2.5 mm) and closed-abdomen HIPEC with mytomicin-C and cisplatin. Previously, 26 patients had systemic chemotherapy. PMP was histologically classified into disseminated peritoneal adenomucinosis (DPAM), peritoneal mucinous carcinomatosis (PMCA), and intermediate/discordant group (ID). Immunohistochemical stains were performed for cytokeratin (CK)-7, CK-20, CDX-2, MUC-2, MUC-5AC, CD-44s. The significance of 22 potential clinical, pathological, and biological prognostic variables was assessed by multivariate analysis.
Adequate cytoreduction was performed in 89 patients, suboptimal cytoreduction in six, palliative surgery in nine. Operative mortality was 1%. Seventy-eight patients were diagnosed with DPAM, 26 with PMCA, and none with ID. Median follow-up was 37 months (range, 1–110) for the overall series. Five-year overall survival (OS) and progression-free survival (PFS) were 78.3% and 31.1%, respectively. At multivariate analysis, adequate cytoreduction, no previous systemic chemotherapy, and DPAM correlated to better OS and PFS, elevated serum CA19.9 correlated only to better PFS. In most cases, CK20, CDX-2, and MUC-2 were diffusely positive, while CK-7, MUC-5AC, and CD44s were variably expressed. CK20 expression correlated to prognosis at univariate analysis.
Favorable outcome after comprehensive treatment can be expected in patients with DPAM, not treated with preoperative systemic chemotherapy and amenable to adequate cytoreduction. MUC-2, CK-20, and CD44s expression may be related to PMP unique biologic behavior.