Cytoreductive Surgery and Intraperitoneal Chemotherapy in Patients with Peritoneal Metastases from Colorectal Cancer : Aspects of loco-regional treatment outcome, patient selection, and chemo-sensitivity

Abstract: Previously, peritoneal metastases(PM) from colorectal cancer(CRC) have been considered a terminal and generalised form of cancer. A new treatment strategy combining cytoreductive surgery(CRS) and intraperitoneal chemotherapy(IPC) has recently shown promising results. The aim of this thesis was to investigate different aspects of this treatment in order to optimise the treatment and to clarify its potential as a new treatment option. Treatment outcome, patient selection, method of IPC (hyperthermic intraperitoneal chemotherapy-HIPEC vs. sequential postoperative intraperitoneal chemotherapy-SPIC) and choice of drugs for IPC were the aspects covered in this thesis.The treatment outcome of CRS and IPC according to the median overall survival ranged from 24 to 34 months with 5-year overall survival ranging from 20 to 40% depending on the IPC treatment administered. Furthermore, the 5-year disease-free survival was impressive at 32% for patients receiving HIPEC. This establishes the curative potential of this treatment. Due to current inadequacies of radiological imaging, a score (Corep score) was developed for patient selection purposes. This score had a sensitivity of 80% and specificity of 100% in identifying patients with short cancer-specific survival after the treatment (<12 months). Further studies are needed to elucidate the clinical usefulness of the Corep score. HIPEC was associated with better survival than the SPIC method at similar morbidity and mortality rates, suggesting that HIPEC be the method of preference. Concerning the choice of drugs, the last study investigated the chemo-sensitivity of different PM tumour-types with a special focus on CRC. While CRC samples were generally more resistant, the ratio of the in vivo concentration compared to the ex vivo concentration giving a 50% tumour cell death showed that oxaliplatin had the best profile across all PM tumour types as well as for CRC. This needs further confirmation in a clinical trial.