Peritoneal malignancy: anatomy, pathophysiology and an update on modern day imaging

With increasing subspecialized experience in radical cytoreductive surgery and intra abdominal chemotherapy for peritoneal malignancy, outcomes have improved significantly in selected patients. The surgery and the treatment regimens are radical and therefore correct patient selection is critical. The radiologist plays a central role in this process by estimating, as precisely as possible, the pre-treatment disease burden. Because of the nature of the disease process, accurate staging is not an easy task. Tumour deposits may be very small and in locations where they are very difficult to detect. It must be acknowledged that no form of modern day imaging has the capability of detecting the smallest peritoneal nodules which may only be visible to direct inspection or histopathological evaluation. Nonetheless, it behoves the radiologist to be as exact and precise as possible in the reporting of this disease process. This is both to select patients who are likely to benefit from radical treatment, and just as importantly, to identify patients who are unlikely to achieve adequate cytoreductive outcomes. In this review, we outline the patterns of spread of disease and the anatomic basis for this, as well as the essential aspects of reporting abdominal studies in this patient group. We provide an evidence-based update on the relative strengths and limitations of our available multimodality imaging techniques namely CT, MRI and PET/CT.

Physical, psychological and nutritional outcomes in a cohort of Irish patients with metastatic peritoneal malignancy scheduled for cytoreductive surgery (CRS) and heated intrapertioneal chemotherapy (HIPEC): An exploratory pilot study

Background Treatment for peritoneal malignancy (PM) can include cytoreductive surgery (CRS) and heated intrapertioneal chemotherapy (HIPEC) and is associated with morbidity and mortality. Physical, psychological and nutritional outcomes are important pre-operatively. The aim of this pilot study was to investigate these outcomes in patients with PM before and after CRS-HIPEC. Methods Between June 2018 and November 2019, participants were recruited to a single-centre study. Primary outcome was cardiopulmonary exercise testing (CPET) variables oxygen uptake (VO2) at anaerobic threshold (AT) and at peak. Secondary outcome measures were upper and lower body strength, health related quality of life (HRQoL) and the surgical fear questionnaire. Exploratory outcomes included body mass index, nutrient intake and post-operative outcome. All participants were asked to undertake assessments pre CRS-HIPEC and 12 weeks following the procedure. Results Thirty-nine patients were screened, 38 were eligible and 16 were recruited. Ten female and 6 male, median (IQR) age 53 (42–63) years. Of the 16 patients recruited, 14 proceeded with CRS-HIPEC and 10 competed the follow up assessment at week 12. Pre-operative VO2 at AT and peak was 16.8 (13.7–18) ml.kg-1.min-1 and 22.2 (19.3–25.3) ml.kg-1.min-1, upper body strength was 25.9 (20.3–41.5) kg, lower body strength was 14 (10.4–20.3) sec, HRQoL (overall health status) was 72.5 (46.3–80) % whilst overall surgical fear was 39 (30.5–51). The VO2 at AT decreased significantly (p = 0.05) and HRQoL improved (p = 0.04) between pre and post- CRS-HIPEC. There were no significant differences for any of the other outcome measures. Conclusion This pilot study showed a significant decrease in VO2 at AT and an improvement in overall HRQoL at the 12 week follow up. The findings will inform a larger study design to investigate a prehabilitation and rehabilitation cancer survivorship programme.

Role of Epithelial–Mesenchymal Plasticity in Pseudomyxoma Peritonei: Implications for Locoregional Treatments

The mechanisms by which neoplastic cells disseminate from the primary tumor to metastatic sites, so-called metastatic organotropism, remain poorly understood. Epithelial–mesenchymal transition (EMT) plays a role in cancer development and progression by converting static epithelial cells into the migratory and microenvironment-interacting mesenchymal cells, and by the modulation of chemoresistance and stemness of tumor cells. Several findings highlight that pathways involved in EMT and its reverse process (mesenchymal–epithelial transition, MET), now collectively called epithelial–mesenchymal plasticity (EMP), play a role in peritoneal metastases. So far, the relevance of factors linked to EMP in a unique peritoneal malignancy such as pseudomyxoma peritonei (PMP) has not been fully elucidated. In this review, we focus on the role of epithelial–mesenchymal dynamics in the metastatic process involving mucinous neoplastic dissemination in the peritoneum. In particular, we discuss the role of expression profiles and phenotypic transitions found in PMP in light of the recent concept of EMP. A better understanding of EMP-associated mechanisms driving peritoneal metastasis will help to provide a more targeted approach for PMP patients selected for locoregional interventions involving cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.