Peritoneal disease: key imaging findings that help in the differential diagnosis

The peritoneum is a unique serosal membrane, which can be the site of primary tumors and, more commonly, secondary pathologic processes. Peritoneal carcinomatosis is the most common malignant process to affect the peritoneal cavity, and the radiologist plays an important role in making the diagnosis and assessing the extent of disease, especially in sites that may hinder surgery. In this review we address the role of the radiologist in the setting of peritoneal pathology, focusing on peritoneal carcinomatosis as this is the predominant malignant process, followed by revising typical imaging findings that can guide the differential diagnosis. We review the most frequent primary and secondary peritoneal tumor and tumor-like lesions, proposing a systemic approach based on clinical history and morphological appearance, namely distinguishing predominantly cystic from solid lesions, both solitary and multiple.

High-Fat Diet-Induced Obese Effects of Adipocyte-Specific CXCR2 Conditional Knockout in the Peritoneal Tumor Microenvironment of Ovarian Cancer

Obesity contributes to ovarian cancer (OC) progression via tumorigenic chemokines. Adipocytes and OC cells highly express CXCR2, and its ligands CXCL1/8, respectively, indicating that the CXCL1/8-CXCR2 axis is a molecular link between obesity and OC. Here, we investigated how the adipocyte-specific CXCR2 conditional knockout (cKO) affected the peritoneal tumor microenvironment of OC in a high-fat diet (HFD)-induced obese mouse model. We first generated adipocyte-specific CXCR2 cKO in mice: adipose tissues were not different in crown-like structures and adipocyte size between the wild-type (WT) and cKO mice but expressed lower levels of CCL2/6 compared to the obese WT mice. HFD-induced obese mice had a shorter survival time than lean mice. Particularly, obese WT and cKO mice developed higher tumors and ascites burdens, respectively. The ascites from the obese cKO mice showed increased vacuole clumps but decreased the floating tumor burden, tumor-attached macrophages, triglyceride, free fatty acid, CCL2, and TNF levels compared to obese WT mice. A tumor analysis revealed that obese cKO mice attenuated inflammatory areas, PCNA, and F4/80 compared to obese WT mice, indicating a reduced tumor burden, and there were positive relationships between the ascites and tumor parameters. Taken together, the adipocyte-specific CXCR2 cKO was associated with obesity-induced ascites despite a reduced tumor burden, likely altering the peritoneal tumor microenvironment of OC.

Inducing, Collecting, and Storing Ascites

Ascitic fluid (also called ascites) is an intraperitoneal fluid extracted from mice that have developed a peritoneal tumor. For antibody production, the tumor is induced by injecting hybridoma cells into the peritoneum, which serves as a growth chamber for the cells. The hybridoma cells grow to high densities and continue to secrete the antibody of interest, thus creating a high-titered solution of antibodies for collection. A single mouse may yield as much as 10 mL of ascitic fluid or as little as 1 mL per batch. Antibody concentrations will typically be between 1 and 10 mg/mL. The most common problem encountered in storing ascites is contamination of these solutions with bacteria or fungi. This can be prevented by the addition of sodium azide.

Defining optimal selection criteria to improve prognosis and avoid futility in surgical resection of colorectal peritoneal metastases.

36 Background: Surgical resection of peritoneal metastases of colorectal cancer (CRC PM) may benefit some patients similar to hepatic metastases. This approach remains controversial in part due to inconsistent selection criteria and reported outcomes. The impact of preoperative clinical characteristics and tumor molecular profiles on survival among surgically treated patients is incompletely understood. The aim of this study was to investigate the relationship between possible predictive variables and survival in a large cohort of patients treated on a standardized clinical pathway and to develop a clinically useful patient selection tool. Methods: This retrospective cohort study utilized the database of the Catalonian peritoneal metastases regional program, established in 2006. The program provides treatment for all PM patients within an autonomous region with a population of 7.5 million and includes a single dedicated high volume surgical unit. We included all adult patients with surgically resected CRC PM. The clinical pathway includes the administration of perioperative (neoadjuvant and adjuvant) systemic chemotherapy and has historically included a dose of heated intraoperative intraperitoneal chemotherapy (HIPEC) at the time of surgery. Demographic and clinical data was analyzed with descriptive statistics. Survival and the associated predictors were analyzed with the Cox proportional hazard model with HRs used to create a predictive nomogram. Results: A total of 538 patients (mean age 59) have been treated with surgery and a complete resection (CC0) was achieved in 94% of cases. Planned preoperative systemic chemotherapy was delivered in 95% of cases, consistent with the clinical pathway. Surgical morbidity was low (urgent reoperation 6.1%, postoperative return to the ICU 2.4%, 30-day readmission 4.3%) as was 30-day mortality (0.4%). After a median follow up of 27.5 months, the median overall survival (OS) was 43.1 months. It varied considerably by subgroup: patients with low peritoneal tumor burden had the highest OS (median 49 months) and those with signet ring cell subtype the lowest (median 19 months). Factors independently associated with survival were: N stage at diagnosis, histological subtype, quantified peritoneal tumor burden (PCI score) and presence of visceral involvement. A selection tool and predictive nomogram were designed incorporating the results of the multivariable analysis. Conclusions: A set of clinical variables can be identified that independently influences patient survival after surgical resection of CRC PM that should be used as selection criteria when considering surgery. With optimized patient selection and treatment within a specialized center, excellent survival and low morbidity can be anticipated following surgery for CRC PM.