HIPEC Using High Intra-abdominal Pressure

Patients affected by peritoneal metastasis from colorectal cancer or pseudomyxoma peritonei, submitted to complete cytoreduction (residual disease \<2.5mm) would be eligible for the study. Residual and resectable tumour nodules of 0.5 to 1.0 cm will be left behind after the cytoreduction and they will be collected at the end of HIPEC for the purpose of this study. HIPEC will be performed using closed abdomen technique and cisplatin (42mg/L of perfusate) + mitomycin-C (3.3mg/m2/L of perfusate) for 60 minutes, at 42.5°C. Patients will be randomly assigned to HIPEC with low IAP (8-12 mmHg) or high IAP (18-22 mmHg). IAP will be measured using bladder catheter. Patients of high IAP group will be strictly monitored during the perfusion regarding hemodynamic/respiratory parameters. During the HIPEC, perfusate and blood samples will be collected every 10 minutes. Additional samples of arterial blood will be collected at 70, 90,120,180 and 240 minutes. After the completion of HIPEC residual tumor tissues, normal peritoneum and muscular fascia will be sampled for determination of cisplatin concentration. Blood samples will be immediately centrifuged to separate plasma. An aliquot of plasma will be stored at -30°C for total platinum determination. Another aliquot will be ultrafiltered by centrifugation through a membrane with a cut-off 5000 Da for ultrafilterable platinum determination. The ultrafiltrate will be stored at -30°C until analysis. Perfusate samples will follow the same procedure of blood samples. Tissues samples will be stored at -80°C until analysis. Platinum determination will be performed using an Inductive Coupled Plasma Mass Spectrometry (ICP-MS) system by Thermo Scientific after preparing calibration curves with atomic platinum. Fluid samples simply dilute before ICP-MS examination while tissues will be desiccated, digested with a mixture of nitric acid and oxygen water, and evaporated to dryness prior to determination. The investigators will compare the following outcomes between the study groups: tumor tissue concentration of cisplatin; the area under the curve (AUC) ratio of perfusate UF concentration of cisplatin times time to plasma UF concentration times time; in-hospital stay; systemic toxicity (NCI-CTCAE.v3), morbidity, and mortality. Thirty eight patients (19 in each group) would be needed to detect an increase cisplatin concentration of 20 ng/mg of tumor tissue if patients are submitted to high-IAP during HIPEC, assuming alfa=0.05 and power=0.90 and standard deviation of 15 ng. Accrual time will be 30 months. The randomized groups will be stratified according to tumor type.