Intraoperative hyperthermia is associated with increased acute kidney injury following cytoreductive surgery and hyperthermic intraperitoneal chemotherapy: a retrospective cohort study.

BACKGROUND: Acute kidney injury (AKI) is common after cytoreduction surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) for peritoneal surface malignancies. Herein we analyzed the association between intraoperative hyperthermia and AKI following CRS-HIPEC. METHODS: In this retrospective cohort study, we collected baseline and perioperative data from patients who underwent CRS-HIPEC mainly for pseudomyxoma peritonei between 2014 and 2020. Nasopharyngeal temperature was recorded at 5-min intervals. The area above the threshold was calculated for intraoperative hyperthermia (>37.0 °C). AKI was diagnosed and classified according to the KDIGO creatinine criteria. A multivariable logistic regression model was established to assess the association between hyperthermia and AKI. RESULTS: A total of 480 patients were included in the analysis. Of these, 10.6% (51/480) developed AKI within 7 postoperative days. After correction for confounding factors, a larger area above the threshold of hyperthermia was significantly associated with an increased risk of AKI (odds ratio [OR] 1.36, 95% CI 1.14-1.63, p = 0.001). Among other factors, older age (OR 1.05, 95% CI 1.02-1.09, p = 0.002), postoperative hypotension requiring vasopressors (OR 2.09, 95% CI 1.02-4.27, p = 0.042), and intraperitoneal chemotherapy containing cisplatin (OR 2.75, 95% CI 1.20-6.33, p = 0.017) were also associated with an increased risk of AKI. Patients with AKI required longer mechanical ventilation, stayed longer in the intensive care unit and hospital, developed more complications, and required more intensive care unit readmission. CONCLUSIONS: Among patients undergoing CRS-HIPEC, intraoperative hyperthermia was independently associated with a higher risk of AKI; this effect was additive to other risk factors including cisplatin-containing chemotherapy.

Targeted Genetic Sequencing Analysis of 223 Cases of Pseudomyxoma Peritonei Treated by Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy Shows Survival Related to GNAS and KRAS Status.

BACKGROUND AND AIM: Pseudomyxoma peritonei (PMP) is an unusual condition with unique behaviour caused by a mucinous neoplasm, usually arising from the appendix. The aim of this study was to evaluate the prevalence of genomic alterations in clinical specimens of PMP using a targeted assay and correlate the findings with clinical, pathological and outcome data. Sequencing data from 223 patients were analysed. RESULTS: The median follow-up interval was 48 months. The primary neoplasm was appendiceal in 216 patients, ovarian in 4, urachal in 2 and renal in one. We confirmed common mutations in GNAS and KRAS (42% each) with significant co-occurrence of variants in these genes. TP53 mutations were found in 8%. Other mutations were rare but included novel mutations in BAP1 and ERBB4. Of 17 patients with acellular peritoneal mucin, 6 (35%) were positive for DNA mutations. The non-appendiceal cases generally showed a similar mutational landscape to the appendiceal lesions with GNAS and KRAS commonly mutated, although one urachal lesion showed multi-hit TP53 mutation without variants in either GNAS or KRAS. Survival was significantly associated with the grade of the primary neoplasm, the grade of the peritoneal disease, the completeness of cytoreduction score and with mutation in either GNAS, KRAS or both. The hazard ratio (HR) associated with mutation in GNAS and/or KRAS was 1.87 (p = 0.004). CONCLUSIONS: Survival outcome was more closely associated with the grade of the peritoneal disease than with the grade of the primary neoplasm. Our findings support the developing concept that mutational analysis may provide prognostic information in patients with PMP.

Molecular Profiling of Low-Grade Appendiceal Mucinous Neoplasms (LAMN).

Low-grade appendiceal mucinous neoplasia (LAMN) represents a relatively rare tumor of the appendix typically diagnosed incidentally through appendectomy for acute appendicitis. In cases where perforation occurs, mucinous content may disseminate into the abdominal cavity, leading to the development of pseudomyxoma peritonei (PMP). The primary objective of this study was to elucidate the molecular characteristics associated with various stages of LAMN and PMP. DNA was extracted from LAMN, primary PMPs, recurrent PMPs, and adenocarcinomas originating from LAMN. The subsequent analysis involved the examination of mutational hotspot regions within 50 cancer-related genes, covering over 2800 COSMIC mutations, utilizing amplicon-based next-generation sequencing (NGS). Our findings revealed activating somatic mutations within the MAPK-signaling pathway across all tumors examined. Specifically, 98.1% of cases showed mutations in KRAS, while one tumor harbored a BRAF mutation. Additionally, GNAS mutations were identified in 55.8% of tumors, with no significant difference observed between LAMN and PMP. While LAMN rarely displayed additional mutations, 42% of primary PMPs and 60% of recurrent PMPs showed additional mutations. Notably, both adenocarcinomas originating from LAMN showed mutations within TP53. Furthermore, 7.7% (4/52) of cases exhibited a potentially targetable KRAS G12C mutation. In four patients, NGS analysis was performed on both primary PMP and recurrent PMP/adenocarcinoma samples. While mutations in KRAS and GNAS were detected in almost all samples, 50% of recurrent cases displayed an additional SMAD4 mutation, suggesting a notable alteration during disease progression. Our findings indicate two key points: First, mutations within the MAPK pathway, particularly in KRAS, are evident across all tumors, along with a high frequency of GNAS mutations. Second, progression toward PMP or adenocarcinoma is associated with an accumulation of additional mutations within common oncogenic pathways.

Bilateral erector spinae plane block by multiple injection for pain control in pseudomyxoma peritonei surgery: a single-blind randomized controlled trial.

OBJECTIVE: Currently, the primary surgical treatment for pseudomyxoma peritonei (PMP) is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). The perioperative period is frequently accompanied by severe pain. Erector spinae plane block (ESPB) can enhance analgesia for abdominal surgery. The purpose of this study was to compare the analgesic effects of bilateral multiple-injection ESPB in patients with PMP. METHODS: Fifty patients with PMP were randomly divided into two groups: the ESPB combined with general anesthesia group (Group E) and the general anesthesia alone group (Group C). Prior to the induction, patients in Group E underwent ESPB at the T7 and T11 levels. The primary outcome was the visual analog scale (VAS) scores during rest at 6 h post-extubation. Secondary outcomes included intraoperative and postoperative opioid consumption, time for first rescue analgesia, frequency distribution of rescue analgesia, incidence of nausea and vomiting, adverse events associated with ESPB. RESULTS: The Visual Analogue Scale (VAS) scores in Group E were significantly lower compared to Group C at immediate post-extubation (1.6 ± 0.9 vs. 2.4 ± 1.2, P = 0.008), and at 2 (1.9 ± 1.2 vs. 3.2 ± 1.1, P < 0.001), 4 (2.4 ± 1.5 vs. 3.7 ± 1.0, P = 0.001), and 6 h (2.7 ± 1.1 vs. 3.8 ± 1.4, P = 0.004) post-extubation during rest. Similarly, the VAS scores in Group E were significantly lower than those in Group C at immediate post-extubation (3.0 ± 1.4 vs. 4.6 ± 1.2, P < 0.001), and at 2 (3.8 ± 1.7 vs. 4.9 ± 1.4, P = 0.019), 4 (3.5 ± 1.3 vs. 5.3 ± 1.5, P < 0.001), and 6 h (3.9 ± 1.8 vs. 4.9 ± 1.3, P = 0.004) post-extubation during movement. In Group E, the intraoperative remifentanil administration (2319.3 ± 1089.5 vs. 2984.6 ± 796.1, P = 0.017) and the amount of rescue analgesia within 2 h post-extubation (0 vs. 4, P = 0.037) were significantly less than in Group C, and the first rescue analgesia time was shorter as well (231.4 ± 147.5 vs. 668.8 ± 416.7, P < 0.001). CONCLUSION: Compared to general anesthesia alone, bilateral multiple-injection ESPB with 0.2% ropivacaine can enhance analgesia and reduce opioid administration in patients with PMP. However, the duration of analgesia with ESPB is relatively short due to the low concentration of the local anesthetic used. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2300069504, 20/03/2023.

Hydatid cysts in the mesocolon mimicking peritoneal pseudomyxoma in a post-appendectomy patient: A case report.

We aimed to present a case of two mesocolonic hydatid cysts that mimicked the presentation of peritoneal pseudomyxoma. Hydatidosis is a zoonotic parasitic infection caused by the cestode Echinococcus spp., whose larval stage affects various organs. The present case describes a 40-year-old male patient who presented with severe lower abdominal pain and was diagnosed with acute appendicitis. The patient underwent an appendectomy and was later referred to an oncology surgery clinic because of imaging findings suggestive of peritoneal pseudomyxoma or carcinomatosis. A video-assisted laparoscopic procedure revealed two cysts and microscopic findings confirmed hydatid cysts. The patient was from a hydatidosis-endemic region of southern Brazil. This case highlights the diagnostic challenges and the need for a multidisciplinary approach and careful histopathological analysis in patients with complex abdominal conditions. This also demonstrates the importance of disseminating knowledge about this condition and its management.

Two-stage cytoreductive surgery for 'extensive' pseudomyxoma peritonei: A legitimate alternative or salvage strategy?

BACKGROUND AND AIM: Two-stage cytoreductive surgery (CRS) has been proposed as an alternative to one-stage surgery in patients who have 'extensive' pseudomyxoma peritonei (PMP) and/or are unfit for very extensive surgery, to reduce morbidity. We review current evidence on two-stage CRS focusing on patient selection, interval between procedures, extent of surgery, use of HIPEC, perioperative and oncological outcomes. METHODS: This is a narrative review. A literature search on PubMed and Embase was performed using keywords- 'Two-stage cytoreductive surgery', 'pseudomyxoma peritonei', 'high-volume PMP', 'huge PMP', 'cytoreductive surgery', 'HIPEC', 'staged surgery' and 'extensive pseudomyxoma peritonei'. RESULTS: Five studies reported outcomes in a total of 114 patients. The indications for two-stage CRS were: in two studies, patients undergoing an incomplete cytoreduction due to undue surgical risk were reevaluated for a second surgery during routine surveillance; severe comorbidities in one; extensive disease with PCI>28 in another and in one, only HIPEC was performed as a second procedure due to intraoperative hemodynamic instability (the two-stage procedure was performed in interest of patient's safety). Major morbidity ranged from 0 to 37.5 % (first-stage) and 25%-38.9 % (second-stage). Short term follow-up demonstrated equivalent short-term oncological outcomes compared to historical data. Long term follow-up and quality-of-life data were not available. CONCLUSIONS: The published studies showed different interpretations and applications of the two-stage CRS concept. The reported morbidity was similar to that after single-stage CRS for extensive PMP. Though short-term survival outcomes are acceptable, long-term follow-up is needed. Planned two-stage CRS should currently be reserved for highly selected clinical situations.

The risk of developing pseudomyxoma peritonei from a non-perforated low grade appendiceal mucinous neoplasm found at appendicectomy.

INTRODUCTION: Low-grade appendiceal mucinous neoplasms (LAMNs) are classified as non-perforated (pTis, pT3) or perforated (pT4), and considered precursors of pseudomyxoma peritonei (PMP). This study aims to quantify the risk of developing PMP from pTis and pT3 LAMNs. MATERIALS AND METHODS: Retrospective analysis of a prospectively collected database identified LAMN patients referred to a specialist centre from 2004 to 2019. pT4 LAMNs and other appendix tumours were excluded. All patients had specialist review of their pathology, operation note, and a CT scan (at least 6 weeks post-operatively). Surveillance CTs were then performed at 6, 12, 24, 36, 48, & 60 months, with tumour markers (CEA, CA19-9, CA125). RESULTS: 193 pT3/pTis LAMN patients were included (pTis = 153, pT3 = 40). Median follow-up = 6.45 (3.91-22.13) years, M:F ratio = 1:1.57, and median age = 57 (23-83) years. Initial surgery included: appendicectomy (67 %), appendicectomy + visceral resection (6 %), and right hemicolectomy (27 %). R1 resections were identified in 5/193 patients (2.5 %). 3 R1 patients underwent re-operation (2 caecal pole excision and 1 ileocecectomy), none of which had residual tumour. 8/193 patients (4 %) were lost to follow up. None of the remaining 185 developed PMP. CONCLUSION: This is the largest reported series of pTis/pT3 LAMNs with standardised follow-up in the literature. LAMNs correctly classified as pT3/pTis (after careful specialist review of pathology, operation note, and a baseline post-operative CT) have negligible risk of developing PMP and should have low intensity surveillance. If completely excised, further surgery is not indicated. R1 resections should be considered on an individual basis at a specialist centre.

Association between preoperative appendiceal histology grade and Pseudomyxoma peritonei grade offers a solution to avoid right hemicolectomy during cytoreductive surgery and HIPEC.

INTRODUCTION & OBJECTIVES: Treatment of PMP consists of appendectomy, cytoreductive surgery (CRS) and HIPEC. Right-sided hemicolectomy is necessary only when PMP is high grade, given the lymphatic invasion risk. To date, no single preoperative factor was identified as predictive of PMP grade. MATERIALS & METHODS: Preoperative factors of a prospective cohort study on PMP were retrospectively analyzed, in order to identify situations linked with high or low grade appendiceal PMP. The main outcome was PMP grade on definitive histology after CRS. RESULTS: n = 105. In univariate analysis, the grade of the appendiceal tumor, systematically reviewed in an expert center, showed an OR of 25.00 (95 % CI: 3.30-189.27; p = 0.001) and an NPV of 93.75 [85.36, 100]. Peritoneal biopsy demonstrated an OR of 19.80 (95 % CI: 2.30-170.71; p = 0.002) and a PPV of 90 [71.41, 100]. In multivariate analysis, these two factors remained significantly associated with PMP grade. CONCLUSION: Whenever appendiceal tumor is low grade on preoperative histology, the colon has to be spared unless completeness of CRS is compromised, which is a high-grade feature in fact. In case of high grade appendiceal tumor and/or peritoneal biopsy, right-sided hemicolectomy is warranted. If no histology is available preoperatively, adapt to intraoperative lesions as no preoperative factors seem to be predictive.

Pseudomyxoma peritonei peritonitis.

Pseudomyxoma peritonei (PMP) is a rare neoplastic condition characterised by gelatinous ascites, which generally arise from mucin-producing appendiceal tumours. Presentation is variable but requires prompt recognition to ensure appropriate specialist management due to risk of malignancy.A male in his 40s presented with a 1-day history of sudden onset, non-migratory abdominal pain, worse in the right iliac fossa. He had no significant medical history nor known drug allergies. Examination revealed right iliac fossa peritonism and blood tests revealed raised inflammatory markers. CT scan showed a right-sided abdominal collection. Intraoperatively, a diagnostic laparoscopy was performed, which revealed extensive mucin in the abdominal cavity. This was washed out and a laparoscopic appendectomy was performed; histopathology confirmed PMP from the ruptured appendix.

Nomogram to Predict Tube Occlusion During Hyperthermic Intraperitoneal Chemotherapy for Pseudomyxoma Peritonei.

OBJECTIVE: To investigate the factors contributing to the blockage of perfusion tubes during hyperthermic intraperitoneal chemotherapy (HIPEC) in patients with appendiceal pseudomyxoma peritonei (PMP) undergoing combined cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy treatment, and to construct a nomogram for predicting the risk of tube occlusion. STUDY DESIGN: Observational study. Place and Duration of the Study: Department of Gastrointestinal Surgery, Central Hospital Affiliated to Shandong First Medical University, Jinan, China, from June 2017 to December 2023. METHODOLOGY: Tube occlusion was defined as the inability to achieve 30 minutes of continuous unobstructed perfusion. Statistical methods such as univariate analysis, multivariate analysis, and Lasso regression were employed for data analysis. RESULTS: The results revealed that 27% of the 383 hyperthermic intraperitoneal chemotherapy perfusion treatments resulted in the tube occlusion events. Multivariate logistic regression analysis identified age, CA-125, CA19-9, and pathological type as the independent risk factors. A nomogram predicting the tube occlusion was constructed and validated for its predictive accuracy and clinical utility. CONCLUSION: This study successfully developed a nomogram to predict the tube occlusion risk during cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy treatment for patients with pseudomyxoma peritonei, providing valuable guidance for clinical practice and aiding in personalised treatment decisions to improve patient prognosis. However, further research is needed to validate the reliability and clinical applicability of the model, as well as to investigate the impact of tube occlusion on treatment outcomes and corresponding management strategies. KEY WORDS: Pseudomyxoma peritonei, Cytoreductive surgery, Hyperthermic intraperitoneal chemotherapy treatment, Tube occlusion, Nomogram.

Mucocoele of the appendix.

Introduction: Mucocoele of the appendix occurs in 0.2-0.7% of people in the world without any well-defined clinical symptoms. It occurs when there is an accumulation of mucous in the lumen of the appendix. Case Presentation: We present three cases: a 48-year-old male admitted to the emergency room with a one-day history of right iliac fossa pain. Abdominal examination was suggestive of acute appendicitis. The initial abdominal computerised tomography scan was reported as being unremarkable. At surgery, a firm tumour of the appendix was found, and a limited right hemicolectomy was done. Histopathology confirmed a mucocoele of the appendix with borderline mucinous histology.The second case is a 63-year-old man who presented with a one-year history of abdominal distension and weight loss. Previous abdominal ultrasound was suggestive of liver cirrhosis with significant ascitic fluid. Abdominal magnetic resonance imaging found an appendix mucocoele with infiltration of the omentum and scalloping of the liver surface suggestive of pseudomyxoma peritonei. A percutaneous biopsy of the omental mass confirmed metastatic mucinous adenocarcinoma of the appendix.The third case is a 68-year-old man who, during an annual medical check-up, had an incidental finding of a cystic right iliac fossa mass on ultrasound, confirmed on abdominopelvic computerised tomography scan to be an appendix mucocele. He had laparoscopic appendicectomy. The histopathological diagnosis confirmed a mucinous cystadenoma of the appendix. Conclusion: Preoperative diagnosis of appendiceal mucocoele is difficult and commonly discovered intraoperatively. The prognosis is good for the histologically benign type, but it is poor when malignant or peritoneal lesions are present. Funding: None declared.

[A Case of Perforated Low-Grade Appendiceal Mucinous Neoplasm Diagnosed During Appendectomy].

A 46-year-old female presented persistent right lower abdominal pain for 4 days. Computed tomography revealed an enlarged appendix with a surrounding low-attenuation mass. The patient was diagnosed with appendiceal abscess-forming appendicitis and initially treated with antibiotics. However, owing to the manifestation of nausea as a side effect, laparoscopic appendectomy was performed 3 days after the initial consultation. Intraoperative examination revealed mucinous material on the surface of the appendix and within the abdominal cavity, leading to the decision to perform an appendectomy with partial cecum resection and excision of the omentum with mucinous deposits. Pathological examination confirmed the diagnosis of a perforating low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei. The patient was subsequently referred to a specialized center for ongoing management, and at 9 months postoperatively, surveillance is being conducted. Low-grade appendiceal mucinous neoplasms can progress to pseudomyxoma peritonei through perforation; however, an optimal treatment approach has not yet been established. In particular, patients in advanced stages of the disease often require challenging management decisions. This case is reported along with a review of the literature to provide further guidance.

Low-grade appendiceal mucinous neoplasms: Histomorphological spectrum in a tertiary care hospital.

BACKGROUND: Low-grade appendiceal mucinous neoplasms (LAMNs) are benign non-invasive epithelial proliferations of the appendix. These usually present clinically as mucoceles and these rarely exceed 2 cm in diameter. Lesions confined to the lumen are labelled as LAMN; however those in which mucin spreads outside the peritoneum are labeled as pseudomyxoma peritonei (PMP). AIMS AND OBJECTIVE: A retrospective study was conducted over a period of three years and all cases of appendectomies were studied. Twelve cases of LAMN were identified, which is a diagnostic dilemma for the pathologists and clinicians. RESULTS: LAMN was identified based on the histopathological features. Out of the 12 cases, 9 were classified as LAMN and 3 as appendiceal neoplasm with PMP. There was villous or flat proliferation of epithelial lining, loss lymphoid aggregates, and dissecting mucin within muscularis. CONCLUSION: LAMNs are rare neoplasms of the appendix, with clinical presentation similar to acute appendicitis. Mucinous collections within the appendiceal wall should be extensively searched for mucosal changes and, if found, should prompt a careful search for pushing invasion of LAMNs. A thorough and vigilant gross examination can be of great help. Appendicectomy is the treatment of benign and grossly intact mucinous neoplasm.

Impact of obesity after cytoreductive surgery and intraperitoneal hyperthermic chemotherapy for rare peritoneal malignancies: Paradox of obesity or poor prognostic factor?

BACKGROUND: Obesity is a public health concern with an increasing occurrence worldwide. Literature regarding impact of obesity on results after management of peritoneal carcinomatosis is poor. Our aim was to compare postoperative and oncological outcomes after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for rare peritoneal malignancies according to the body mass index. METHODS: All the patients managed by cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for rare peritoneal malignancies (including mainly pseudomyxoma peritonei and peritoneal mesothelioma), between 1995 and 2020, were retrospectively included from the French national registry of rare peritoneal tumors. RESULTS: 1450 patients were retrospectively included (63.5 % female, mean age 54 ± 13 years). Patients were divided into two groups according to their body mass index: non-obese (n = 1248, 86 %) and obese (n = 202, 14 %). Overall morbidity was significantly lower in non-obese patients in comparison with obese patients (n = 532/1248, 43 % vs n = 106/202, 53 %, p = 0.009). Medical and surgical morbidities were significantly lower in non-obese patients in comparison with obese patients (423/1258, 34 % vs n = 86/202, 43 %, p = 0.02 and n = 321/1248, 26 % vs n = 67/202, 33 %, p = 0.003, respectively). One-, 5- and 10-year overall survivals were similar between non-obese and obese patients (95 %, 82 % and 70 % vs 94 %, 76 % and 63 %; p = 0.1). One-, 5- and 10-year disease free survivals were similar between non-obese and obese patients (84 %, 67 % and 61 % vs 79 %, 62 % and 56 %, p = 0.1). CONCLUSION: Obese patients have to be carefully managed after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for rare peritoneal malignancies. Some perioperative prophylactic treatments could be specifically implemented to reduce thromboembolic events, metabolic and wound complications.

Precision Oncology and Systemic Targeted Therapy in Pseudomyxoma Peritonei.

PURPOSE: Pseudomyxoma peritonei (PMP) is a rare and poorly understood malignant condition characterized by the accumulation of intra-abdominal mucin produced from peritoneal metastases. Currently, cytoreductive surgery remains the mainstay of treatment but disease recurrence and death after relapse frequently occur in patients with PMP. New therapeutic strategies are therefore urgently needed for these patients. EXPERIMENTAL DESIGN: A total of 120 PMP samples from 50 patients were processed to generate a collection of 50 patient-derived organoid (PDO) and xenograft (PDX) models. Whole exome sequencing, immunohistochemistry analyses, and in vitro and in vivo drug efficacy studies were performed. RESULTS: In this study, we have generated a collection of PMP preclinical models and identified druggable targets, including BRAFV600E, KRASG12C, and KRASG12D, that could also be detected in intra-abdominal mucin biopsies of patients with PMP using droplet digital PCR. Preclinical models preserved the histopathological markers from the original patient sample. The BRAFV600E inhibitor encorafenib reduced cell viability of BRAFV600E PMP-PDO models. Proof-of-concept in vivo experiments showed that a systemic treatment with encorafenib significantly reduced tumor growth and prolonged survival in subcutaneous and orthotopic BRAFV600E-PMP-PDX mouse models. CONCLUSIONS: Our study demonstrates for the first time that systemic targeted therapies can effectively control PMP tumors. BRAF signaling pathway inhibition represents a new therapeutic opportunity for patients with BRAFV600E PMP who have a poor prognosis. Importantly, our present data and collection of preclinical models pave the way for evaluating the efficacy of other systemic targeted therapies toward extending the promise of precision oncology to patients with PMP.

The 2022 PSOGI International Consensus on HIPEC Regimens for Peritoneal Malignancies: Pseudomyxoma Peritonei.

BACKGROUND: The combination of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) constitutes the established standard of care for pseudomyxoma peritonei patients. However, the role of HIPEC lacks validation through randomized trials, leading to diverse proposed treatment protocols. This consensus seeks to standardize HIPEC regimens and identify research priorities for enhanced clarity. METHODS: The steering committee applied the patient, intervention, comparator, and outcome method to formulate crucial clinical questions. Evaluation of evidence followed the Grading of Recommendations, Assessment, Development, and Evaluation system. Consensus on HIPEC regimens and research priorities was sought through a two-round Delphi process involving international experts. RESULTS: Out of 90 eligible panelists, 71 (79%) participated in both Delphi rounds, resulting in a consensus on six out of seven questions related to HIPEC regimens. An overwhelming 84% positive consensus favored combining HIPEC with CRS, while a 70% weak positive consensus supported HIPEC after incomplete CRS. Specific HIPEC regimens also gained consensus, with 53% supporting Oxaliplatin 200 mg/m2 and 51% favoring the combination of cisplatin (CDDP) associated with mitomycin-C (MMC). High-dose MMC regimens received an 89% positive recommendation. In terms of research priorities, 61% of panelists highlighted the importance of studies comparing HIPEC regimens post CRS. The preferred regimens for such studies were the combination of CDDP/MMC and high-dose MMC. CONCLUSIONS: The consensus recommends the application of HIPEC following CRS based on the available evidence. The combination of CDDP/MMC and high-dose MMC regimens are endorsed for both current clinical practice and future research efforts.

Progress on immuno-microenvironment and immune-related therapies in patients with pseudomyxoma peritonei.

Pseudomyxoma peritonei (PMP) is an indolent malignant syndrome. The standard treatment for PMP is cytoreductive surgery combined with intraperitoneal hyperthermic chemotherapy (CRS + HIPEC). However, the high recurrence rate and latent clinical symptoms and signs are major obstacles to further improving clinical outcomes. Moreover, patients in advanced stages receive little benefit from CRS + HIPEC due to widespread intraperitoneal metastases. Another challenge in PMP treatment involves the progressive sclerosis of PMP cell-secreted mucus, which is often increased due to activating mutations in the gene coding for guanine nucleotide-binding protein alpha subunit (GNAS). Consequently, the development of other PMP therapies is urgently needed. Several immune-related therapies have shown promise, including the use of bacterium-derived non-specific immunogenic agents, radio-immunotherapeutic agents, and tumor cell-derived neoantigens, but a well-recognized immunotherapy has not been established. In this review the roles of GNAS mutations in the promotion of mucin secretion and disease development are discussed. In addition, the immunologic features of the PMP microenvironment and immune-associated treatments are discussed to summarize the current understanding of key features of the disease and to facilitate the development of immunotherapies.

Pseudomyxoma peritonei leading to "jelly belly" abdomen: a case report and review of the literature.

BACKGROUND: Pseudomyxoma peritonei is an infrequent condition with a global annual incidence of only one to two cases per million people. Mucinous neoplasms, widespread intraperitoneal implants, and mucinous ascites characterize it. Currently, most clinicians misdiagnose this condition, which leads to delayed management. CASE PRESENTATION: A 44-year-old North Indian female presented with a 1.5-month history of an abdominal lump. Physical examination revealed a sizeable abdominopelvic mass at 36 weeks. Contrast-enhanced computed tomography showed a massive multiloculated right ovarian cystic mass measuring 28 × 23 × 13 cm with mild ascites and elevated carcinoembryonic antigen levels (113.75 ng/ml). A provisional diagnosis of ovarian mucinous neoplasm was made, for which the patient underwent laparotomy. Intraoperatively, there were gross mucinous ascites, along with a large, circumscribed, ruptured right ovarian tumor filled with gelatinous material. The appendicular lump was also filled with mucinous material along with the omentum, ascending colon, right lateral aspect of the rectum, splenic surface, and small bowel mesentery. Cytoreductive surgery was performed along with an oncosurgeon, including total abdominal hysterectomy with bilateral salpingoophorectomy, omentectomy, right hemicolectomy, lower anterior resection, ileo-transverse stapled anastomosis with proximal ileal loop diversion stoma, excision of multiple peritoneal gelatinous implants, and peritoneal lavage. Histopathology and immunohistochemistry confirmed the presence of intestinal-type mucinous carcinoma. Postoperatively, the patient was given six cycles of chemotherapy. She tolerated it without any specific morbidity and had an uneventful recovery. Postoperative follow-up at 15 months revealed normal tumor marker levels and abdominal computed tomography findings and no signs suggestive of local recurrence or distal metastases. CONCLUSIONS: Pseudomyxoma peritonei is a rare disease that is frequently misdiagnosed in the preoperative phase. Therefore, radiologists and clinicians should maintain a high index of suspicion for accurate diagnosis and multidisciplinary management.

Omental metastases in patients with pseudomyxoma peritonei or colorectal peritoneal metastases - is routine omentectomy justified?

BACKGROUND: The greater omentum is routinely resected during cytoreductive surgery (CRS), but few studies have analyzed the rationale behind this. This study aimed to assess the prevalence of omental metastases (OM) and the correlation between macroscopically suspected and microscopically confirmed OM, in patients with pseudomyxoma peritonei (PMP) or colorectal peritoneal metastases (PM). METHOD: All patients without previous omentectomy, treated with initial CRS and hyperthermic intraperitoneal chemotherapy for PMP or colorectal PM, at Uppsala University Hospital in 2013-2021, were included. Macroscopic OM in surgical reports was compared with histopathological analyses. RESULTS: In all, 276 patients were included. In those with PMP, 112 (98%) underwent omentectomy and 67 (59%) had macroscopic suspicion of OM. In 5 (4%) patients, the surgeon was uncertain. Histopathology confirmed OM in 81 (72%). In patients with macroscopic suspicion, 96% had confirmed OM (positive predictive value, PPV). In patients with no suspicion, 24% had occult OM (negative predictive value, NPV = 76%). In patients with colorectal PM, 156 (96%) underwent omentectomy and 97 (60%) had macroscopic suspicion. For 5 (3%) patients, the surgeon was uncertain. OM was microscopically confirmed in 90 (58%). PPV was 85% and NPV was 89%. The presence of OM was a univariate risk factor for death in PMP (HR 3.62, 95%CI 1.08-12.1) and colorectal PM (HR 1.67, 95%CI 1.07-2.60), but not in multivariate analyses. CONCLUSION: OM was common and there was a high risk of missing occult OM in both PMP and colorectal PM. These results support the practice of routine omentectomy during CRS.