Stemness and hybrid epithelial-mesenchymal profiles guide peritoneal dissemination of malignant mesothelioma and pseudomyxoma peritonei.

Intrabdominal dissemination of malignant mesothelioma (MM) and pseudomyxoma peritonei (PMP) is poorly characterized with respect to the stemness window which malignant cells activate during their reshaping on the epithelial-mesenchymal (E/M) axis. To gain insights into stemness properties and their prognostic significance in these rarer forms of peritoneal metastases (PM), primary tumor cultures from 55 patients selected for cytoreductive surgery with hyperthermic intraperitoneal chemotherapy were analyzed for cancer stem cells (CSC) by aldehyde dehydrogenase 1 (ALDH1) and spheroid formation assays, and for expression of a set of plasticity-related genes to measure E/M transition (EMT) score. Intratumor heterogeneity was also analyzed. Samples from PM of colorectal cancer were included for comparison. Molecular data were confirmed using principal component and cluster analyses. Associations with survival were evaluated using Kaplan-Meier and Cox regression models. The activity of acetylsalicylic acid (ASA), a stemness modifier, was tested in five cultures. Significantly increased amounts of ALDH1bright-cells identified high-grade PMP, and discriminated solid masses from ascitic/mucin-embedded tumor cells in both forms of PM. Epithelial/early hybrid EMT scores and an early hybrid expression pattern correlated with pluripotency factors were significantly associated with early peritoneal progression (p = .0343 and p = .0339, respectively, log-rank test) in multivariable models. ASA impaired spheroid formation and increased cisplatin sensitivity in all five cultures. These data suggest that CSC subpopulations and hybrid E/M states may guide peritoneal spread of MM and PMP. Stemness could be exploited as targetable vulnerability to increase chemosensitivity and improve patient outcomes. Additional research is needed to confirm these preliminary data.

Predictors of Financial Toxicity Risk Among Patients Undergoing Cytoreductive Surgery with Hyperthermic Intraperitoneal Chemotherapy (CRS-HIPEC).

BACKGROUND: Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is the preferred treatment for select patients with peritoneal malignancies. However, the procedure is resource intensive and costly. This study aimed to determine the risk of financial toxicity for patients undergoing CRS-HIPEC. PATIENTS AND METHODS: We performed a retrospective cohort study of patients undergoing CRS-HIPEC at a single institution from 2016 to 2022. We utilized insurance status, out-of-pocket expenditures, and estimated post-subsistence income to determine risk of financial toxicity. A multivariable logistic regression was used to determine risk factors for financial toxicity. RESULTS: Our final study cohort consisted of 163 patients. Average age was 58 [standard deviation 10] years, and 52.8% (n = 86) were male. A total of 52 patients (31.9%) were at risk of financial toxicity. A total of 36 patients (22.1%) were from the lower income quartiles (first or second) and 127 patients (77.9%) were from the higher income quartiles (third or fourth). A total of 47 patients (29%) were insured by Medicare, and 116 patients (71%) had private insurance. The median out-of-pocket expenditure across the study cohort was $3500, with a median of $5000 ($3341-$7350) for the at-risk group and $3341 ($2500-$4022) for the not at-risk group (p < 0.001). Risk factors for financial toxicity included high out-of-pocket expenditures and a lower income quartile. CONCLUSIONS: An estimated one-third of patients undergoing CRS-HIPEC at our institution were at risk for financial toxicity. Several preoperative factors were associated with an increased risk and could be utilized to identify patients who might benefit from interventions.

Genetic Clustering of Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy Patients of Colorectal Origin: KRAS and Not TP53 Cluster Alterations are Associated with Poor Outcomes.

BACKGROUND: The prognostic impact of genetic mutations for patients who undergo cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) of colorectal origin (CRC) is not well defined. OBJECTIVE: We aimed to describe the genetic classifications in an unsupervised fashion, and the outcomes of this patient population. METHODS: A retrospective, bi-institutional study was performed on patients who underwent CRS-HIPEC with targeted mutation data with a median follow-up time of 61 months. Functional link analysis was performed using STRING v11.5. Genes with similar functional significance were clustered using unsupervised k-means clustering. Chi-square, Kaplan-Meier, and the log-rank test were used for comparative statistics. RESULTS: Sixty-four patients with peritoneal carcinomatosis from CRC origin underwent CRS-HIPEC between 2007 and 2022 and genetic mutation data were extracted. We identified 19 unique altered genes, with KRAS (56%), TP53 (33%), and APC (22%) being the most commonly altered; 12.5% had co-altered KRAS/TP53. After creating an interactome map, k-means clustering revealed three functional clusters. Reactome Pathway analysis on three clusters showed unique pathways (1): Ras/FGFR3 signaling; (2) p53 signaling; and (3): NOTCH signaling. Seventy-one percent of patients in cluster 1 had KRAS mutations and a median overall survival of 52.3 months (p < 0.05). CONCLUSIONS: Patients with peritoneal carcinomatosis (PC) of CRC origin who underwent CRS-HIPEC and with tumors that harbored mutations in cluster 1 (Ras/FGFR3 signaling) had worse outcomes. Pathway disruption and a cluster-centric perspective may affect prognosis more than individual genetic alterations in patients with PC of CRC origin.

Adoption of an Enhanced Recovery After Surgery Protocol Increases Cost of Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy and Does not Improve Outcomes.

BACKGROUND: Enhanced recovery after surgery (ERAS) protocols have been shown to reduce length of stay (LOS) and complications. The impact of ERAS protocols on the cost of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) has not been studied. PATIENTS AND METHODS: We performed a retrospective cohort analysis of patients undergoing CRS-HIPEC from 2016-2022 at a single quaternary center. Propensity score matching was used to create pre-and post-ERAS cohorts. Cost, overall and serious complications, and intensive care unit (ICU) length of stay (LOS) between the two cohorts were compared using the Mann-Whitney U-test for continuous variables and χ2 test for categorical variables. RESULTS: Our final matched cohort consisted of 100 patients, with 50 patients in both the pre- and post-ERAS groups. After adjusting for patient complexity and inflation, the median total cost [$75,932 ($67,166-102,645) versus $92,992 ($80,720-116,710), p = 0.02] and operating room cost [$26,817 ($23,378-33,121) versus $34,434 ($28,085-$41,379), p < 0.001] were significantly higher in the post-ERAS cohort. Overall morbidity (n = 22, 44% versus n = 17, 34%, p = 0.40) and ICU length of stay [2 days (IQR 1-3) versus 2 days (IQR 1-4), p = 0.70] were similar between the two cohorts. A total cost increase of $22,393 [SE $13,047, 95% CI (-$3178 to $47,965), p = 0.086] was estimated after implementation of ERAS, with operating room cost significantly contributing to this increase [$8419, SE $1628, 95% CI ($5228-11,609), p < 0.001]. CONCLUSIONS: CRS-HIPEC ERAS protocols were associated with higher total costs due to increased operating room costs at a single institution. There was no significant difference in ICU LOS and complications after the implementation of the ERAS protocol.

Reclassification of Appendiceal Mucinous Neoplasms and Associated Pseudomyxoma Peritonei According to the Peritoneal Surface Oncology Group International Consensus: Clinicopathological Reflections of a Two-Center Cohort Study.

BACKGROUND: International consensus on classifications of appendiceal mucinous neoplasms (AMNs) and associated pseudomyxoma peritonei (PMP) have been carefully made but clinicopathological associations supporting decision making remain scarce. OBJECTIVE: This study aimed to assess interdependence between AMNs and PMP and provide directions for clinical management. METHODS: This two-center retrospective cohort study reviewed patients with PMP treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy between 2005 and 2021. The primary objective was to reassess histopathologic grade of AMNs and PMP according to the Peritoneal Surface Oncology Group International classification and to establish its interdependence. Secondary outcomes were recurrence rate, PMP grade progression, ovarian involvement, and overall survival (OS). RESULTS: Of 105 patients included, 78 (74.3%) had low-grade AMNs as the primary tumor, 8 (7.6%) had high-grade AMNs, 7 (6.7%) had mucinous adenocarcinoma (MAC), 1 (0.9%) had MAC with signet ring cells (SRC), and 11 (10.5%) had unidentified tumors. Overall, 11 patients (10.5%) had no PMP, 21 (20.0%) had acellular mucin, 56 (53.3%) had low-grade PMP, 12 (11.4%) had high-grade PMP, and 5 (4.8%) had PMP-SRC. In 11 cases (13.3%), AMNs and matching PMP grade differed. Over a 16-year follow-up, recurrence occurred in 31.8%, with three cases showing histopathologically changed PMP. Ovarian involvement was observed in 43/65 females (66.2%). Median OS was 13.8 years, and 5-year OS rates were 100%, 74.4%, 44.4%, and 20% for acellular mucin, low-grade PMP, high-grade PMP and PMP-SRC, respectively (p < 0.001). CONCLUSIONS: AMN histology does not always reflects its associated PMP grade, while PMP grade strongly influences survival. Ovarian involvement and recurrent PMP showing unchanged histopathological features are common.

Systemic chemotherapy in addition to CRS-HIPEC for colorectal peritoneal metastases: A critical systematic review on the impact on overall survival.

In patients with resectable colorectal peritoneal metastases, it is unclear whether systemic chemotherapy, in addition to cytoreductive surgery-hyperthermic intraperitoneal chemotherapy (CRS-HIPEC), improves overall survival (OS). This systematic review of 12 retrospective studies involving 3721 patients aimed to summarize the available evidence. Contradictory results were found regarding the effectiveness of neoadjuvant, adjuvant, and perioperative systemic therapies on OS, with a high risk of bias. Available evidence remains inconclusive, stressing the need for prospective, randomized trials, like the ongoing Dutch CAIRO6-trial.

A machine learning approach for predicting textbook outcome after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

INTRODUCTION: Peritoneal carcinomatosis is considered a late-stage manifestation of neoplastic diseases. Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) can be an effective treatment for these patients. However, the procedure is associated with significant morbidity. Our aim was to develop a machine learning model to predict the probability of achieving textbook outcome (TO) after CRS-HIPEC using only preoperatively known variables. METHODS: Adult patients with peritoneal carcinomatosis and who underwent CRS-HIPEC were included from a large, single-center, prospectively maintained dataset (2001-2020). TO was defined as a hospital length of stay ≤14 days and no postoperative adverse events including any complications, reoperation, readmission, and mortality within 90 days. Four models (logistic regression, neural network, random forest, and XGBoost) were trained, validated, and a user-friendly risk calculator was then developed. RESULTS: A total of 1954 CRS-HIPEC procedures for peritoneal carcinomatosis were included. Overall, 13% (n = 258) achieved TO following CRS-HIPEC procedure. XGBoost and logistic regression had the highest area under the curve (AUC) (0.76) after model optimization, followed by random forest (AUC 0.75) and neural network (AUC 0.74). The top preoperative variables associated with achieving a TO were lower peritoneal cancer index scores, not undergoing proctectomy, splenectomy, or partial colectomy and being asymptomatic from peritoneal metastases prior to surgery. CONCLUSION: This is a data-driven study to predict the probability of achieving TO after CRS-HIPEC. The proposed pipeline has the potential to not only identify patients for whom surgery is not associated with prohibitive risk, but also aid surgeons in communicating this risk to patients.

Immune profile of patients with peritoneal carcinomatosis selected for CRS-HIPEC therapy.

Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is a treatment option for peritoneal carcinomatosis (PC) from colorectal cancer (CRC), which is otherwise a terminal stage of disease. Nevertheless, survival outcomes are only marginally superior to other treatments. This fact highlights the need for better strategies to control intra-abdominal disease recurrence after CRS-HIPEC, including the complementary use of immunotherapies. The aim of this study was therefore to investigate the immune phenotype of T cells in patients with PC. Fifty three patients with CRC (34 patients with PC and 19 patients without PC) were enrolled in a prospective study (clinicaltrials.gov: NCT04108936). Peripheral blood and omental fat were collected to isolate peripheral blood mononuclear cells (PBMCs) and adipose tissue mononuclear cells (ATMCs). These cells were analysed by flow cytometry using a panel focused upon T cell memory differentiation and exhaustion markers. We found a more naïve profile for CD8+ T cells in peripheral blood and intra-abdominal fat of PC patients compared to comparator group (CG) patients. Furthermore, there was an over-representation of CD4+ T cells expressing inhibitory receptors in adipose tissue of PC patients, but not in blood. Our description of intraperitoneal T cell subsets gives us a better understanding of how peritoneal carcinomatosis shapes local immune responses.

A total neoadjuvant chemotherapy approach is associated with improved recurrence-free survival in patients with colorectal peritoneal metastases undergoing cytoreductive surgery and HIPEC.

BACKGROUND: The primary aim of this study is to evaluate the oncologic outcomes of two popular systemic chemotherapy approaches in patients with colorectal peritoneal metastases (CPM) undergoing cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). METHODS: We performed a dual-center retrospective review of consecutive patients who underwent CRS-HIPEC for CPM due to high or intermediate-grade colorectal cancer. Patients in the total neoadjuvant therapy (TNT) group received 6 months of preoperative chemotherapy. Patients in the "sandwich" (SAND) chemotherapy group received 3 months of preoperative chemotherapy with a maximum of 3 months of postoperative chemotherapy. RESULTS: A total of 34 (43%) patients were included in the TNT group and 45 (57%) patients in the SAND group. The median overall survival (OS) in the TNT and SAND groups were 77 and 61 months, respectively (p = 0.8). Patients in the TNT group had significantly longer recurrence-free survival (RFS) than the SAND group (29 vs. 12 months, p = 0.02). In a multivariable analysis, the TNT approach was independently associated with improved RFS. CONCLUSION: In this retrospective study, a TNT approach was associated with improved RFS, but not OS when compared with a SAND approach. Further prospective studies are needed to examine these systemic chemotherapeutic approaches in patients with CPM undergoing CRS-HIPEC.

Expression of PD-L1 in Patients With Malignant Peritoneal Mesothelioma: A Pilot Study.

INTRODUCTION: Frequency of PD-L1 expression and the role of immunotherapy in malignant peritoneal mesothelioma (MPM) have not been well characterized. The purpose of this study was to determine PD-L1 expression in patients with MPM and perform an exploratory analysis for associations between PD-L1 and its biological behavior in MPM. METHODS: Tumor samples were collected from patients undergoing surgical interventions between January 2018 and June 2020. Specimens were stained with anti-PD-L1 antibodies (Dako 22c3) and positivity was determined by tumor proportion score (TPS) or combined positive score (CPS) being ≥1%. RESULTS: Twenty one samples were obtained from 21 patients. Sixteen of 21 (76%) samples were CPS positive and 9 of 21 (43%) were TPS positive. Three samples had more aggressive biphasic/sarcomatoid histology and a high CPS and TPS (CPS: 3, 75, 95%; TPS: 2, 60, 90%). On an exploratory analysis, as the CPS or TPS threshold increased, there was a trend towards worse survival. CONCLUSIONS: MPM has a high frequency of PD-L1 expression, which may be associated with more aggressive tumor biology. These data provide the foundation for continued evaluation of checkpoint inhibition in patients with MPM.

Unusual site of pseudomyxoma peritonei recurrence after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy: a case report of intraluminal disease manifestation in the small bowel.

BACKGROUND: Pseudomyxoma peritonei (PMP) is an uncommon clinical condition characterized by the presence of mucinous ascites, mainly induced by perforated appendiceal mucinous neoplasms (AMN). The peritoneal surface of the small bowel is usually spared from disease manifestation due to peristaltic movements. Mucinous tumours can disseminate as PMP on the entire peritoneum, but are rarely intraluminal. For the first time in literature, we report a case of intraluminal PMP involving the ileum. CASE PRESENTATION: A 75-year-old male was treated for perforated AMN and disseminated PMP with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. During follow-up, the patient developed intraperitoneal recurrence together with intraluminal depositions in the ileum, both disease manifestations with identical KRAS and SMAD4 mutations. Hereafter, the patient was treated with palliative care. CONCLUSION: This case illustrates the variation in the biological and clinical behaviour of this rare disease. Clinicians should be aware of unusual tumour distribution patterns of PMP, including the presence of mucinous tumour within the small bowel.

Dedicated MRI staging versus surgical staging of peritoneal metastases in colorectal cancer patients considered for CRS-HIPEC; the DISCO randomized multicenter trial.

BACKGROUND: Selecting patients with peritoneal metastases from colorectal cancer (CRCPM) who might benefit from cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is challenging. Computed tomography generally underestimates the peritoneal tumor load. Diagnostic laparoscopy is often used to determine whether patients are amenable for surgery. Magnetic resonance imaging (MRI) has shown to be accurate in predicting completeness of CRS. The aim of this study is to determine whether MRI can effectively reduce the need for surgical staging. METHODS: The study is designed as a multicenter randomized controlled trial (RCT) of colorectal cancer patients who are deemed eligible for CRS-HIPEC after conventional CT staging. Patients are randomly assigned to either MRI based staging (arm A) or to standard surgical staging with or without laparoscopy (arm B). In arm A, MRI assessment will determine whether patients are eligible for CRS-HIPEC. In borderline cases, an additional diagnostic laparoscopy is advised. The primary outcome is the number of unnecessary surgical procedures in both arms defined as: all surgeries in patients with definitely inoperable disease (PCI > 24) or explorative surgeries in patients with limited disease (PCI < 15). Secondary outcomes include correlations between surgical findings and MRI findings, cost-effectiveness, and quality of life (QOL) analysis. CONCLUSION: This randomized trial determines whether MRI can effectively replace surgical staging in patients with CRCPM considered for CRS-HIPEC. TRIAL REGISTRATION: Registered in the clinical trials registry of U.S. National Library of Medicine under NCT04231175 .

Surgical and oncological outcomes after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy at a nonacademic center: 25-year experience.

BACKGROUND: Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is predominantly performed and studied in academic centers. While developing CRS/HIPEC programs in nonacademic hospitals can increase accessibility, its safety and oncological efficacy remains unclear. We evaluated CRS/HIPEC outcomes in a nonacademic setting. METHODS: A single-center descriptive study was conducted using a prospective database. Data of all CRS/HIPEC attempts in peritoneal surface malignancies (PSM) patients from October 1994 to November 2019 were extracted. Surgical and survival outcomes were measured. Center experience was assessed by quartiles of cases. RESULTS: Overall, 856 patients underwent 948 CRS/HIPEC attempts: 788 (83%) completed CRS/HIPECs, 144 (15%) aborted HIPECs, and 16 (2%) complete cytoreductions (CC-0/1) without chemoperfusion. For completed CRS/HIPECs, median peritoneal cancer index was 24 (interquartile range: 10-33) and CC-0/1 rate was 88%. Major complications occurred in 23.5% with 30- and 100-day mortality of 1.0% and 2.3%, respectively. Median overall survival was 68 months (95% confidence interval [CI]: 50-86). Median progression-free survival was 37 months (95%CI: 28-46). Incomplete cytoreduction and major complication rates decreased over time, while mortality remained low and constant. CONCLUSIONS: CRS/HIPEC at a nonacademic center with advanced surgical and auxiliary services is a safe option to treat PSM with favorable surgical and oncological outcomes.

The role of molecular biomarkers in outcomes and patient selection for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for peritoneal metastases of colorectal origin.

BACKGROUND: Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is effective in select patients with peritoneal metastases of colorectal (CRC) origin. The impact of different biomarkers in predicting recurrence after CRS/HIPEC is unclear. METHODS: Retrospective review of patients who underwent CRS/HIPEC for PC of CRC origin from 03/2007-08/2017. Molecular profile of the primary tumor was obtained from pathology reports, whenever available. RESULTS: Overall, 100 patients underwent CRS/HIPEC for peritoneal metastases of CRC origin. Most patients presented high grade tumor histology (G2/G3, n = 97, 97%), and a majority showed mucinous features (n = 61, 61%). At a median follow-up of 18 months, median DFS for the overall population was 13 months (95% CI 9.6, 16.4). Data reporting at least one mutational analysis was available in 64 patients. Microsatellite stability was detected in 42/50 (84%) patients, mKRAS in 25/51 (49%), and mBRAF in 5/35 (14.3%). On Kaplan-Meier analysis, BRAF was the only mutation associated with poor DFS (16 months, CI 95% 11.7-43.3 vs. 7 months, CI 95% 2.1-11.9, p = .008). On multivariate analysis, mBRAF independently predicted earlier recurrence (p = .032). CONCLUSIONS: In this analysis, mBRAF was independently associated with earlier recurrence in patients undergoing CRS/HIPEC for CRC, leading to dismal median DFS (7 months). Strict patient selection is advisable in these patients.

Epidemiology and risks for infection following cytoreductive surgery and hyperthermic intra-peritoneal chemotherapy.

BACKGROUND: CRS-HIPEC is associated with improved cancer survival but an increased risk of infection. METHODS: Consecutive patients undergoing CRS-HIPEC between January 2016 and May 2018 were retrospectively reviewed. Malignancy type, comorbidities, perioperative risk factors and infectious complications were captured, using standardised definitions. Association between risk factors and infection outcomes was evaluated by logistic regression modelling. RESULTS: One-hundred patients underwent CRS-HIPEC, predominantly for colorectal cancer and pseudomyxoma peritonei. Overall, 43 (43.0%) experienced an infectious complication, including infections at surgical site (27), respiratory tract (9), urinary tract (11), Clostridium difficile (2) and post-operative sepsis (15). In most, infection onset was within 7 days post-operatively. Median length of hospitalisation was 19 days for patients with infection, compared to 8 days for those without (p = 0.000). There were no deaths at 60 days. Of variables potentially associated with surgical site infection, small bowel resection (OR 4.01, 95% confidence interval [CI] 1.53-10.83; p = 0.005) and number of resected viscera (OR 1.41, 95% CI 1.00-1.98; p = 0.048) were significantly associated with infection. CONCLUSIONS: We demonstrate a significant burden of early infective complications in patients undergoing CRS-HIPEC. Higher-risk subgroups, including those with small bowel resection and increased number of resected viscera, may benefit from enhanced monitoring.

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.

[Outcome of Icelandic patients undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) abroad].

BACKGROUND: Peritoneal carcinomatosis is a known complication of colorectal cancer and has long been considered very difficult to manage. The survival has been reported to be under two years after systemic chemotherapy with or without palliative surgery. The most recent method of treatment is compiled of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) and has been suggested to significantly increase survival. The aim of this study was to research the cases of Icelandic patients undergoing this treatment overseas and the impact it has had on their disease. METHODS: A retrospective study of all Icelandic patients who have undergone CRS-HIPEC treatment abroad 2008-2017. Information was retrieved from medical records and from registry of the Icelandic Health Insurance committee of medical treatments abroad. RESULTS: A total of 11 patients have undergone CRS-HIPEC treatment after having received their initial treatment in Landspitali University Hospital. All of the surgeries were performed in the United States by the same surgeon in the years 2008-2017. The group consists of 10 women and 1 man with a mean age of 53 years. The cause of peritoneal carcinomatosis was appendiceal cancer for 7 patients (67%) and colon cancer for 3 patients (27%). One patient had a primary malignancy of the peritoneum, mesothelioma. Three patients suffered complications within 30 days of surgery, 2 had infection and 1 had an anastomotic leak. Another patient had a late complication of bowel stenosis and later a fistula. Five patients have completed their five year observation period post surgery without diagnosis of recurrence and mean follow-up time was 44 months. Out of 11 patients, 10 are still alive. Five have been diagnosed with recurrence of disease. CONCLUSION: Icelandic patients who have undergone CRS-HIPEC treatment have in most cases done well and survival is comparable to other studies. Half of the survivors did not have recurrence of disease within 5 years of surgery. Prognosis has improved since the introduction of this treatment and every reason to keep sending selected Icelandic patients abroad to receive it.

Hospital readmission rates and risk factors for readmission following cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal surface malignancies.

BACKGROUND: Cytoreductive surgery and Hyperthermic intra-peritoneal chemotherapy (CRS/HIPEC) for peritoneal surface malignancies is associated with high morbidity. The increased numbers of patients undergoing CRS/HIPEC in recent years mandates risk analysis and quality assurance. However, only scarce data exist regarding causative parameters for readmission. The aim of this study was to assess readmission rates and risk factors associated with readmission. METHODS: A retrospective-cohort study including patients from two high-volume centers who underwent CRS/HIPEC surgery between the years 2007-2016 was performed. Patients' demographics, peri-operative data and readmission rates were recorded. RESULTS: 223 patients were included in the study. The 7 and 30-day readmission rates were 3.5% (n = 8) and 11% (n = 25), respectively. Late readmission rates (up to 90 days) were 11% (n = 25). The most common causes of readmission were surgical related infections (35%), small bowel obstruction (17.5%) and dehydration (14%). Post-operative complications were associated with higher readmission rates (p = 0.0001). PCI score was not associated with higher rates of readmission. CONCLUSION: Readmissions following CRS/HIPEC occur mainly due to infectious complications and dehydrations. Patients following CRS/HIPEC should be discharged after careful investigation to a community based continuing care with access for IV fluid replacement or antibiotics administration when required.