SMYD5 methylation of rpL40 links ribosomal output to gastric cancer.

Dysregulated transcription due to disruption in histone lysine methylation dynamics is an established contributor to tumorigenesis1,2. However, whether analogous pathologic epigenetic mechanisms act directly on the ribosome to advance oncogenesis is unclear. Here we find that trimethylation of the core ribosomal protein L40 (rpL40) at lysine 22 (rpL40K22me3) by the lysine methyltransferase SMYD5 regulates mRNA translation output to promote malignant progression of gastric adenocarcinoma (GAC) with lethal peritoneal ascites. A biochemical-proteomics strategy identifies the monoubiquitin fusion protein partner rpL40 (ref. 3) as the principal physiological substrate of SMYD5 across diverse samples. Inhibiting the SMYD5-rpL40K22me3 axis in GAC cell lines reprogrammes protein synthesis to attenuate oncogenic gene expression signatures. SMYD5 and rpL40K22me3 are upregulated in samples from patients with GAC and negatively correlate with clinical outcomes. SMYD5 ablation in vivo in familial and sporadic mouse models of malignant GAC blocks metastatic disease, including peritoneal carcinomatosis. Suppressing SMYD5 methylation of rpL40 inhibits human cancer cell and patient-derived GAC xenograft growth and renders them hypersensitive to inhibitors of PI3K and mTOR. Finally, combining SMYD5 depletion with PI3K-mTOR inhibition and chimeric antigen receptor T cell administration cures an otherwise lethal in vivo mouse model of aggressive GAC-derived peritoneal carcinomatosis. Together, our work uncovers a ribosome-based epigenetic mechanism that facilitates the evolution of malignant GAC and proposes SMYD5 targeting as part of a potential combination therapy to treat this cancer.

ΔNp73 and its effector targets promote colorectal peritoneal carcinosis and predict survival.

Peritoneal metastasis of colorectal origin appears in ~10-15% of patients at the time of diagnosis and in 30-40% of cases with disease progression. Locoregional spread through the peritoneum is considered stage IVc and is associated with a poor prognosis. The development of a regional therapeutic strategy based on cytoreductive surgery, and hyperthermic intra-abdominal chemotherapy has significantly altered the course of the disease. Although recent evidence supports the benefits of cytoreductive surgery, the benefits of hyperthermic intra-abdominal chemotherapy are, however, still a matter of debate. Understanding the molecular alterations underlying the disease is crucial for developing new therapeutic strategies. Here, we evaluated the involvement in peritoneal dissemination of the oncogenic isoform of TP73, ΔNp73, and its effector targets in in vitro and mouse models, and in 30 patients diagnosed with colorectal peritoneal metastasis. In an orthotopic mouse model, we observed that tumor cells overexpressing ΔNp73 present a higher avidity for the peritoneum and that extracellular vesicles secreted by ΔNp73-upregulating tumor cells enhance their dissemination. In addition, we identified that tumor cells overexpressing ΔNp73 present with dysregulation of genes associated with an epithelial/mesothelial-to-mesenchymal transition (MMT) and that mesothelial cells exposed to the conditioned medium of tumor cells with upregulated ΔNp73 present a mesenchymal phenotype. Lastly, ΔNp73 and its effector target RNAs were dysregulated in our patient series, there were positive correlations between ΔNp73 and its effector targets, and MSN and ITGB4 (ΔNp73 effectors) predicted patient survival. In conclusion, ΔNp73 and its effector targets are involved in the peritoneal dissemination of colorectal cancer and predict patient survival. The promotion of the EMT/MMT and modulation of the adhesion capacity in colorectal cancer cells might be the mechanisms triggered by ΔNp73. Remarkably, ΔNp73 protein is a druggable protein and should be the focus of future studies. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Ascites microenvironment conditions the peritoneal pre-metastatic niche to promote the implantation of ovarian tumor spheroids: Involvement of fibrinogen/fibrin and αV and α5ß1 integrins.

At least one-third of patients with epithelial ovarian cancer (OC) present ascites at diagnosis and almost all have ascites at recurrence especially because of the propensity of the OC cells to spread in the abdominal cavity leading to peritoneal metastasis. The influence of ascites on the development of pre-metastatic niches, and on the biological mechanisms leading to cancer cell colonization of the mesothelium, remains poorly understood. Here, we show that ascites weakens the mesothelium by affecting the morphology of mesothelial cells and by destabilizing their distribution in the cell cycle. Ascites also causes destabilization of the integrity of mesothelium by modifying the organization of cell junctions, but it does not affect the synthesis of N-cadherin and ZO-1 by mesothelial cells. Moreover, ascites induces disorganization of focal contacts and causes actin cytoskeletal reorganization potentially dependent on the activity of Rac1. Ascites allows the densification and reorganization of ECM proteins of the mesothelium, especially fibrinogen/fibrin, and indicates that it is a source of the fibrinogen and fibrin surrounding OC spheroids. The fibrin in ascites leads to the adhesion of OC spheroids to the mesothelium, and ascites promotes their disaggregation followed by the clearance of mesothelial cells. Both αV and α5ß1 integrins are involved. In conclusion ascites and its fibrinogen/fibrin composition affects the integrity of the mesothelium and promotes the integrin-dependent implantation of OC spheroids in the mesothelium.

Metastasis-associated fibroblasts in peritoneal surface malignancies.

Over decades, peritoneal surface malignancies (PSMs) have been associated with limited treatment options and poor prognosis. However, advancements in perioperative systemic chemotherapy, cytoreductive surgery (CRS), and hyperthermic intraperitoneal chemotherapy (HIPEC) have significantly improved clinical outcomes. PSMs predominantly result from the spread of intra-abdominal neoplasia, which then form secondary peritoneal metastases. Colorectal, ovarian, and gastric cancers are the most common contributors. Despite diverse primary origins, the uniqueness of the peritoneum microenvironment shapes the common features of PSMs. Peritoneal metastization involves complex interactions between tumour cells and the peritoneal microenvironment. Fibroblasts play a crucial role, contributing to tumour development, progression, and therapy resistance. Peritoneal metastasis-associated fibroblasts (MAFs) in PSMs exhibit high heterogeneity. Single-cell RNA sequencing technology has revealed that immune-regulatory cancer-associated fibroblasts (iCAFs) seem to be the most prevalent subtype in PSMs. In addition, other major subtypes as myofibroblastic CAFs (myCAFs) and matrix CAFs (mCAFs) were frequently observed across PSMs studies. Peritoneal MAFs are suggested to originate from mesothelial cells, submesothelial fibroblasts, pericytes, endothelial cells, and omental-resident cells. This plasticity and heterogeneity of CAFs contribute to the complex microenvironment in PSMs, impacting treatment responses. Understanding these interactions is crucial for developing targeted and local therapies to improve PSMs patient outcomes.

Cell-cell contact-dependent secretion of large-extracellular vesicles from EFNBhigh cancer cells accelerates peritoneal dissemination.

BACKGROUND: Large non-apoptotic vesicles released from the plasma membrane protrusions are classified as large-EVs (LEVs). However, the triggers of LEV secretion and their functions in tumors remain unknown. METHODS: Coculture system of cancer cells, peritoneal mesothelial cells (PMCs), and macrophages (MΦs) was conducted to observe cell-cell contact-mediated LEV secretion. Lineage tracing of PMCs was performed using Wt1CreERT2-tdTnu mice to explore the effects of LEVs on PMCs in vivo, and lymphangiogenesis was assessed by qRT-PCR and flow-cytometry. RESULTS: In peritoneal dissemination, cancer cells expressing Ephrin-B (EFNB) secreted LEVs upon the contact with PMCs expressing ephrin type-B (EphB) receptors, which degraded mesothelial barrier by augmenting mesothelial-mesenchymal transition. LEVs were incorporated in subpleural MΦs, and these MΦs transdifferentiated into lymphatic endothelial cells (LEC) and integrated into the lymphatic vessels. LEC differentiation was also induced in PMCs by interacting with LEV-treated MΦs, which promoted lymphangiogenesis. Mechanistically, activation of RhoA-ROCK pathway through EFNB reverse signaling induced LEV secretion. EFNBs on LEVs activated EphB forward signaling in PMC and MΦs, activating Akt, ERK and TGF-ß1 pathway, which were indispensable for causing MMT and LEC differentiation. LEVs accelerated peritoneal dissemination and lymphatic invasions by cancer cells. Blocking of EFNBs on LEVs using EphB-Fc-fusion protein attenuated these events. CONCLUSIONS: EFNBhigh cancer cells scattered LEVs when they attached to PMCs, which augmented the local reactions of PMC and MΦ (MMT and lymphangiogenesis) and exaggerated peritoneal dissemination.

Safety and efficacy of sirolimus in recurrent intravenous leiomyomatosis, pulmonary benign metastatic leiomyomatosis, and leiomyomatosis peritonealis disseminata: a pilot study.

BACKGROUND: Intravenous leiomyomatosis (IVL), pulmonary benign metastatic leiomyomatosis (PBML), and leiomyomatosis peritonealis disseminata (LPD) are leiomyomas with special growth patterns and high postoperative recurrence rates. We report the safety and efficacy of a pilot study of sirolimus in the treatment of recurrent IVL, PBML, and recurrent LPD. METHODS: This was a pilot study to evaluate the safety and efficacy of sirolimus in the treatment of leiomyomatosis (ClinicalTrials.gov identifier NCT03500367) conducted in China. Patients received oral sirolimus 2 mg once a day for a maximum of 60 months or until disease progression, intolerable toxicity, withdrawal of consent, or investigator decision to stop. The primary end point of this study was the objective response rate. Secondary end points included safety and tolerability, disease control rate, and progression-free survival. RESULTS: A total of 15 patients with leiomyomatosis were included in the study, including five with recurrent IVL, eight with PBML and two with recurrent LPD. The median follow-up time was 15 months (range 6-54 months), nine patients (60%) had treatment-related adverse events (including all levels), and two patients had treatment-related grade 3 or 4 adverse events. The objective response rate was 20.0% (95% CI, 7.1-45.2%), and the disease control rate was 86.7% (95% CI, 62.1-96.3%). Partial response was achieved in three patients. The median response time in the three partial response patients was 33 months (range 29-36 months), and the sustained remission time of these three patients reached 0, 18, and 25 months, respectively. CONCLUSIONS: Sirolimus was safe and effective in the treatment of recurrent IVL, PBML, and recurrent LPD. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT03500367. Registered on 18 April 2018.

Enhanced anti-tumor efficacy with multi-transgene armed mesenchymal stem cells for treating peritoneal carcinomatosis.

BACKGROUND: Mesenchymal stem cells (MSCs) have garnered significant interest for their tumor-tropic property, making them potential therapeutic delivery vehicles for cancer treatment. We have previously shown the significant anti-tumour activity in mice preclinical models and companion animals with naturally occurring cancers using non-virally engineered MSCs with a therapeutic transgene encoding cytosine deaminase and uracil phosphoribosyl transferase (CDUPRT) and green fluorescent protein (GFP). Clinical studies have shown improved response rate with combinatorial treatment of 5-fluorouracil and Interferon-beta (IFNb) in peritoneal carcinomatosis (PC). However, high systemic toxicities have limited the clinical use of such a regime. METHODS: In this study, we evaluated the feasibility of intraperitoneal administration of non-virally engineered MSCs to co-deliver CDUPRT/5-Flucytosine prodrug system and IFNb to potentially enhance the cGAS-STING signalling axis. Here, MSCs were engineered to express CDUPRT or CDUPRT-IFNb. Expression of CDUPRT and IFNb was confirmed by flow cytometry and ELISA, respectively. The anti-cancer efficacy of the engineered MSCs was evaluated in both in vitro and in vivo model. ES2, HT-29 and Colo-205 were cocultured with engineered MSCs at various ratio. The cell viability with or without 5-flucytosine was measured with MTS assay. To further compare the anti-cancer efficacy of the engineered MSCs, peritoneal carcinomatosis mouse model was established by intraperitoneal injection of luciferase expressing ES2 stable cells. The tumour burden was measured through bioluminescence tracking. RESULTS: Firstly, there was no changes in phenotypes of MSCs despite high expression of the transgene encoding CDUPRT and IFNb (CDUPRT-IFNb). Transwell migration assays and in-vivo tracking suggested the co-expression of multiple transgenes did not impact migratory capability of the MSCs. The superiority of CDUPRT-IFNb over CDUPRT expressing MSCs was demonstrated in ES2, HT-29 and Colo-205 in-vitro. Similar observations were observed in an intraperitoneal ES2 ovarian cancer xenograft model. The growth of tumor mass was inhibited by ~ 90% and 46% in the mice treated with MSCs expressing CDUPRT-IFNb or CDUPRT, respectively. CONCLUSIONS: Taken together, these results established the effectiveness of MSCs co-expressing CDUPRT and IFNb in controlling and targeting PC growth. This study lay the foundation for the development of clinical trial using multigene-armed MSCs for PC.

Outcomes Following Cytoreductive Surgery and Hyperthermic Intraoperative Thoraco-Abdominal Chemotherapy with Diaphragm Resection for Peritoneal Carcinomatosis: A Retrospective Cohort Study.

PURPOSE: We aimed to evaluate the safety and efficacy of hyperthermic intraoperative thoraco-abdominal chemotherapy (HITAC) and cytoreductive surgery (CRS) for peritoneal carcinomatosis (PC) patients who underwent diaphragm resection. METHODS: PC patients who underwent CRS with diaphragm resection were selected from a prospectively established database and were divided into hyperthermic intraperitoneal chemotherapy (HIPEC) and HITAC groups. The clinicopathological characteristics, treatment-related variables, perioperative adverse events (AEs), and survival outcomes were compared between the two groups. RESULTS: Of 1168 CRS + HIPEC/HITACs, 102 patients were enrolled-61 HITAC patients and 41 HIPEC patients. In the HITAC and HIPEC groups, the incidence of grade III-V AEs was 29.5% versus 34.1% (p = 0.621). The pleural progression rates were 13.2 versus 18.9% (p = 0.462) and the median overall survival (OS) was 50.5 versus 52.7 months (p = 0.958). Median time to progression (TTP) in thoracic disease was not reached. There was no significant difference in perioperative AEs, TTP, and OS for total patients and the completeness of cytoreduction (CC) score subgroups (p > 0.05). Age ≥ 60 years (hazard ratio [HR] 4.162, p = 0.026) was an independent risk factor influencing pleural progression, and primary malignant peritoneal mesothelioma (MPM; HR 2.749, p = 0.016) and the presence of two or more serious AEs (SAEs; HR 7.294, p = 0.001) were independent risk factors influencing OS. CONCLUSIONS: HITAC can be performed in carefully selected PC patients who underwent diaphragm resection, with no worsening of the safety profile and a possible benefit for pleural progression. In those patients, age ≥ 60 years is associated with a shorter TTP of thoracic disease, while primary MPM and two or more perioperative SAEs are associated with worse OS.

Does Hospital Operative Volume Influence the Outcomes of Patients After Heated Intraperitoneal Chemotherapy for Peritoneal Carcinomatosis?

BACKGROUND: For some cancer operations, center volume is associated with improved patient outcomes. Whether this association is true for cytoreductive surgery/heated intraperitoneal chemotherapy (CRS/HIPEC) is unclear. Given the rapidly expanding use of CRS/HIPEC, the aim of this analysis was to determine whether a volume-outcome relationship exists for this strategy. METHODS: The Vizient Clinical Database® was queried for CRS/HIPEC cases from January 2020 through December 2022. Low-, medium-, and high-volume designations were made by sorting hospitals by case volume and creating equal tertiles based on total number of cases. Analysis was performed via one-way ANOVA with post-hoc Tukey test, as indicated. RESULTS: In the 36-month study period, 5165 cases were identified across 149 hospitals. Low- (n = 113), medium- (n = 25), and high-volume (n = 11) centers performed a median of 4, 21, and 47 cases per annum, respectively. Most cases were performed for appendiceal (39.3%) followed by gynecologic neoplasms (20.4%). Groups were similar with respect to age, gender, race, comorbidities, and histology. Low-volume centers were more likely to utilize the ICU post-operatively (59.6% vs. 40.5% vs. 36.3%; p = 0.02). No differences were observed in morbidity (9.4% vs. 7.1% vs. 9.0%, p = 0.71), mortality (0.9% vs. 0.6% vs. 0.7%, p = 0.93), length of stay (9.3 vs. 9.4 vs. 10 days, p = 0.83), 30-day readmissions (5.6% vs. 5.6% vs. 5.6%, p = 1.0), or total cost among groups. CONCLUSIONS: No association was found between CRS/HIPEC hospital volume and post-operative outcomes. These data suggest that in academic medical centers with HIPEC programs, outcomes for commonly treated cancers are not associated with hospital volume.

Clinical Effectiveness of Preoperative 18F-FDG PET/CT in Predicting Pathological Tumor Grade in Patients with Pseudomyxoma Peritonei Originating from Appendix: A Retrospective Cohort Study.

BACKGROUND: Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy is the standard treatment for patients with pseudomyxoma peritonei (PMP). In some malignancies, the standard uptake value of positron emission tomography with 2-deoxy-2-18F-fluoro-D-glucose integrated with computed tomography (18F-FDG PET/CT) is now accepted as a reliable indicator of neoplastic behavior. This study aimed to evaluate the association between the maximum standardized uptake value (SUVmax) and pathological grade in patients with PMP and to investigate the significance of SUVmax in the preoperative assessment of these patients. PATIENTS AND METHODS: In this retrospective single-center study, consecutively enrolled patients diagnosed with PMP of appendiceal origin underwent preoperative 18F-FDG PET/CT. SUVmax was calculated as the highest SUVmax value in the abdomen excluding the primary site. SUVmax was compared with the pathological grade (low or high grade) of PMP tumors according to the World Health Organization classification and further analyzed with respect to the estimated cutoff point, sensitivity, specificity, and receiver operating characteristic. RESULTS: In total, 160 patients were included. CRS was successfully performed in 93 patients and palliative debulking surgery in 67 patients. The pathological grade was high in 45 patients and low in 115. High-grade patients had a higher median SUVmax on 18F-FDG PET/CT than did low-grade patients (3.83 versus 2.34, p < 0.001). The highest area under the curve was 0.81, with a sensitivity of 77.8%, specificity of 72.3%, and cutoff point of 2.63. CONCLUSION: This study suggests that the SUVmax of preoperative 18F-FDG PET/CT is associated with the pathological grade in patients with PMP.

Repeat Cytoreduction and Hyperthermic Intraperitoneal Chemotherapy for Recurrent Mucinous Appendiceal Adenocarcinoma: A Viable Treatment Strategy with Demonstrable Benefit.

INTRODUCTION: Many patients with mucinous appendiceal adenocarcinoma experience peritoneal recurrence despite complete cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Prior work has demonstrated that repeat CRS/HIPEC can prolong survival in select patients. We sought to validate these findings using outcomes from a high-volume center. PATIENTS AND METHODS: Patients with mucinous appendiceal adenocarcinoma who underwent CRS/HIPEC at MD Anderson Cancer Center between 2004 and 2021 were stratified by whether they underwent CRS/HIPEC for recurrent disease or as part of initial treatment. Only patients who underwent complete CRS/HIPEC were included. Initial and recurrent groups were compared. RESULTS: Of 437 CRS/HIPECs performed for mucinous appendiceal adenocarcinoma, 50 (11.4%) were for recurrent disease. Patients who underwent CRS/HIPEC for recurrent disease were more often treated with an oxaliplatin or cisplatin perfusion (35%/44% recurrent vs. 4%/1% initial, p < 0.001), had a longer operative time (median 629 min recurrent vs. 511 min initial, p = 0.002), and had a lower median length of stay (10 days repeat vs. 13 days initial, p < 0.001). Thirty-day complication and 90-day mortality rates did not differ between groups. Both cohorts enjoyed comparable recurrence free survival (p = 0.82). Compared with patients with recurrence treated with systemic chemotherapy alone, this select cohort of patients undergoing repeat CRS/HIPEC enjoyed better overall survival (p < 0.001). CONCLUSIONS: In appropriately selected patients with recurrent appendiceal mucinous adenocarcinoma, CRS/HIPEC can provide survival benefit equivalent to primary CRS/HIPEC and that may be superior to that conferred by systemic therapy alone in select patients. These patients should receive care at a high-volume center in the context of a multidisciplinary team.

Cost Analysis and Financial Implications of a Peritoneal Surface Malignancy Program in the USA.

BACKGROUND: We aimed to describe the financial implications of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) in the USA. MATERIALS AND METHODS: We conducted a retrospective cost analysis of 100 CRS/HIPEC procedures to examine the impact of patient and procedural factors on hospital costs and reimbursement. A comparison of surgeons' work relative value units (wRVUs) between CRS/HIPEC and a representative sample of complex surgical oncology procedures was made to assess the physicians' compensation rate. Univariable and multivariable backward logistic regression was used to analyze the association between perioperative variables and high direct cost (HDCs). RESULTS: The median direct cost per CRS/HIPEC procedure was US $44,770. The median hospital reimbursement was US $43,066, while professional reimbursement was US $8608, resulting in a positive contribution margin of US $7493/procedure. However, the contribution margin significantly varied with the payer mix. Privately insured patients had a positive median contribution margin of US $23,033, whereas Medicare-insured patients had a negative contribution margin of US $13,034. Length of stay (LOS) had the most significant association with HDC, and major complications had the most significant association with LOS. Finally, CRS/HIPEC procedures generated a median of 13 wRVU/h, which is significantly lower than the wRVU/h generated by open pancreatoduodenectomies, open gastrectomies, and hepatectomies. However, higher operation complexity and multiple visceral resections help compensate for the relatively low wRVU/h. CONCLUSIONS: CRS/HIPEC is an expensive operation, and prolonged LOS has the most significant impact on the total cost of the procedure. High-quality care is essential to improve patient outcomes and maintain the economic sustainability of the procedure.

Clinical Characteristics and Outcomes of Patients with Well-Differentiated Papillary Peritoneal Mesothelial Tumors.

PURPOSE: Well-differentiated papillary peritoneal mesothelial tumors (WDPMTs) are understudied and discrete from peritoneal mesotheliomas (PMs). We report clinicopathologic characteristics and outcomes of a large prospective WDPMT cohort. METHODS: Patients with WDPMT identified between August 2007 and December 2020 were followed through January 2023. Clinical characteristics and outcomes were annotated. Overall survival (OS) was assessed from pathologic diagnosis. Germline variants were analyzed, and targeted next-generation sequencing (NGS; MSK-IMPACT) data were compared to PMs and diffuse pleural mesotheliomas (DPMs). RESULTS: Among 54 patients, median age at diagnosis was 55 (range 20-76), 50% were female (n = 27), and 46% were smokers (n = 25; median 8 pack/years). Most (94%, n = 51) WDPMTs were found during surgical explorations for other indications, primarily other malignancies. Two patients underwent surgical resection for WDPMT; none received systemic therapy for WDPMT. Median OS was not reached (19/54; median follow up 4.5 years). Somatic NGS was available for 35% (19/54) of patients. TRAF7 alterations were enriched in WDPMT (89%; 17/19) compared with PM (0%; 0/50; p < 0.0001) and DPM (0%; 0/74; p < 0.0001). In WDPMT compared with PM and DPM, there were less BAP1 (0% [0/0] vs. 4% [8/50] vs. 46% [34/74]; p = 0.001 and p < 0.0001, respectively) and NF2 (0% [0/0] vs. 24% [12/50] vs. 31% [23/74]; p = 0.03 and p = 0.001 respectively) alterations. Pathogenic germline variants were present in 23% (4/17) of WDPMTs. CONCLUSIONS: Well-differentiated papillary peritoneal mesothelial tumors were primarily incidental findings. There was no WDPMT-related mortality, so there was no distinct role for routine cytoreductive surgery or systemic therapy. Genomic profiles can help to differentiate WDPMT from DPM and PM.

Mesothelioma in situ of the peritoneum: report of three cases and review of the literature.

AIM: Diagnosis of mesothelioma in situ (MIS) is historically controversial and, until recently, specific features defining the entity have not been well characterized. Most reported cases of MIS occurred in the pleura; peritoneal MIS is very rare. This study investigates the morphologic features and results of ancillary testing in peritoneal MIS. METHODS: We present three patients with peritoneal MIS, as defined by a single layer of mesothelial cells with loss of nuclear BRCA-1-associated protein-1 (BAP1) immunostaining and without evidence of invasive tumour by microscopic evaluation, imaging, or direct examination of the peritoneum. Histology and immunostains were reviewed by three expert thoracic pathologists with multidisciplinary input. Next-generation sequencing (NGS) was performed in all three cases. A literature review was conducted to characterize this rare precursor lesion. RESULTS: BAP1 was lost in all three lesions, while methylthioadenosine phosphorylase (MTAP) was retained in two (not performed in the third). NGS revealed BAP1 pathogenic alterations in all three cases as well as mutations of SMO, ERCC3, TET2, and U2AF1. Progression to invasive mesothelioma occurred in one patient at 13 months postdiagnosis (case 1). One patient was diagnosed at age 24 and was later found to harbour a BAP1 germline mutation (case 3). CONCLUSION: This work describes the histologic features and clinicopathologic characteristics of peritoneal MIS in three cases, highlights BAP1 somatic and germline mutations in peritoneal MIS, and strengthens the importance of ancillary studies (including immunohistochemical and molecular studies) in the diagnosis of MIS.

Does serous tubal intraepithelial carcinoma (STIC) metastasize? The clonal relationship between STIC and subsequent high-grade serous carcinoma in BRCA1/2 mutation carriers several years after risk-reducing salpingo-oophorectomy.

OBJECTIVE: The majority of high-grade serous carcinomas (HGSC) of the ovary, fallopian tube, and peritoneum arise from the precursor lesion called serous tubal intraepithelial carcinoma (STIC). It has been postulated that cells from STICs exfoliate into the peritoneal cavity and give rise to peritoneal HGSC several years later. While co-existent STICs and HGSCs have been reported to share similarities in their mutational profiles, clonal relationship between temporally distant STICs and HGSCs have been infrequently studied and the natural history of STICs remains poorly understood. METHODS: We performed focused searches in two national databases from the Netherlands and identified a series of BRCA1/2 germline pathogenic variant (GPV) carriers (n = 7) who had STIC, and no detectable invasive carcinoma, at the time of their risk-reducing salpingo-oophorectomy (RRSO), and later developed peritoneal HGSC. The clonal relationship between these STICs and HGSCs was investigated by comparing their genetic mutational profile by performing next-generation targeted sequencing. RESULTS: Identical pathogenic mutations and loss of heterozygosity of TP53 were identified in the STICs and HGSCs of five of the seven patients (71%), confirming the clonal relationship of the lesions. Median interval for developing HGSC after RRSO was 59 months (range: 24-118 months). CONCLUSION: Our results indicate that cells from STIC can shed into the peritoneal cavity and give rise to HGSC after long lag periods in BRCA1/2 GPV carriers, and argues in favor of the hypothesis that STIC lesions may metastasize.

Intensifying supportive care is associated with improved survival in gastric cancer patients with malignant ascites.

BACKGROUND: Gastric cancer patients with malignant ascites often have poor functional status and malnutrition that preclude receipt of systemic therapies. Thus, these patients have a very poor prognosis. Beginning in 2019, our multidisciplinary gastric cancer disease-oriented team implemented a more aggressive supportive care plan for gastric cancer patients with malignant ascites. The initiative included measures such as supplemental enteral nutrition, ascites drainage, and initiation of chemotherapy on an inpatient basis. We compared outcomes for gastric cancer patients who presented with synchronous malignant ascites treated before and after the implementation of the care plan. METHODS: We performed a retrospective review of our institutional database to identify patients diagnosed with gastric adenocarcinoma and synchronous malignant ascites between 2010 and 2022. We compared overall survival (OS) between patients diagnosed from 2010 to 2018, which will be referred to as the historical control era and patients diagnosed from 2019 to 2022, which will be called the aggressive supportive care era. RESULTS: Fifty-four patients were included in our analysis; 31 patients were treated in the historical control time frame, and 23 patients were treated during the aggressive supportive care era. Demographic, clinical, and pathologic characteristics were similar between groups. 3% of historical controls received supplemental tube feeds at diagnosis as compared to 30% of the aggressive supportive care cohort (p < 0.01). 3% of historical controls received their first cycle of chemotherapy in the inpatient setting versus 39% of patients treated during the aggressive supportive care era (p < 0.01). The median number of chemotherapy cycles received was 5 among historical controls and 9.5 among aggressive supportive care era patients (p = 0.02). There was no difference in the number of days spent as an inpatient between the two groups. The median OS for historical control patients was 5.4 months as compared with 10.4 months for patients treated during aggressive supportive care era (p = 0.04). CONCLUSIONS: Gastric cancer patients with synchronous malignant ascites treated during a timeframe when our multidisciplinary team implemented more aggressive supportive care measures had improved OS as compared with historic controls. Our results suggest that aggressive supportive measures for these patients with highly challenging clinical issues and poor prognosis can prolong survival. Specifically, initiation of chemotherapy in the inpatient setting and supplemental nutrition should be considered for patients at high risk for treatment intolerance.

Critical reappraisal of prognostic indicators for 949 mucinous appendiceal neoplasm patients.

BACKGROUND AND OBJECTIVES: The standard of care for treatment of an appendiceal mucinous neoplasm with peritoneal dissemination is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). These two treatments are combined in the operating room. A crucial requirement for benefit long-term is proper patient selection. Clinical and histopathologic prognostic indicators are used, along with the patient's fitness for surgery, to select patients to receive CRS and HIPEC. METHODS: This study seeks to identify the reliable prognostic indicators for four different groups of patients. They are (1) the low-grade appendiceal mucinous neoplasms (LAMN) with a complete CRS, (2) the mucinous appendiceal adenocarcinomas (MACA) with complete CRS, (3) MACA with lymph node metastases (MACA-LN) with complete CRS, and (4) all histologic subtypes with incomplete cytoreduction. The prognostic indicators were evaluated for their impact on overall survival in these four groups of patients. RESULTS: The completeness of cytoreduction (CC) score statistically significantly showed survival differences in all three histologic subtypes. The peritoneal cancer index (PCI) showed significance with LAMN and MACA-LN but not with MACA and not with incomplete CRS. The prior surgical score (PSS) was a prognostic indicator that predicted the outcome with LAMN, MACA-LN, and incomplete CRS patients but not with the MACA group. Patients who were symptomatic or who had extensive systemic chemotherapy before CRS had a significantly reduced survival. CONCLUSION: The utility of prognostic indicators varied greatly within our four different groups of appendiceal mucinous neoplasms. CC score was always a reliable prognosticator. Surprisingly, PCI was not.

Research progress of malignant peritoneal mesothelioma with paraneoplastic syndrome: A review.

Malignant peritoneal mesothelioma (MPM) is a rare and invasive tumor, and some patients will develop paraneoplastic syndrome (PS) during the course of the disease. This review summarizes PS associated with MPM, focusing on the clinical characteristics and treatment progress in hematological, endocrine, rheumatic, neurological, urinary, and other systems to decrease missed diagnosis and misdiagnosis, help early diagnosis and prompt treatment, and provide guidance for the clinical decision-making of this kind of patients.

Molecular Surrogate Subtypes of Ovarian and Peritoneal Low-grade Serous Carcinoma.

Low-grade serous carcinoma (LGSC) is an uncommon histotype of ovarian carcinoma, accounting for ~3% of cases. There is evidence that survival of peritoneal LGSC (pLGSC) is longer than that of ovarian LGSC (oLGSC). Key molecular alterations of LGSC have been established, including loss of CDKN2A and PR expression, MAPK pathway alterations, and loss of USP9X expression. We hypothesized that LGSC could be subclassified into clinically applicable molecular subtypes by a few surrogate tests similar to endometrioid carcinomas using a hierarchical decision tree based on the strength of the prognostic associations of the individual alterations. Our study included 71 LGSCs. Immunohistochemistry for CDKN2A, ER, PR, NF1, and USP9X and sequencing for KRAS , NRAS , and BRAF were performed. Our data showed the co-occurrence of key molecular alterations, and despite suggestive trends, hierarchical molecular subtyping did not provide significantly different stratification of patients according to survival in this cohort. We confirmed that patients diagnosed with pLGSC have a longer survival than high-stage oLGSC, with the intriguing observation that normal CDKN2A and PR status were associated with excellent survival in pLGSC. Therefore, CDKN2A and PR status might aid in the classification of indeterminate implants, where abnormal findings favor pLGSC over noninvasive implants. Molecular subtypes should be further evaluated in larger cohorts for their prognostic and potentially predictive value.

A comparative in vivo study of hyperthermic intraperitoneal chemotherapy with cisplatin versus doxorubicin versus cisplatin plus doxorubicin for the treatment of intra-abdominally disseminated alveolar rhabdomyosarcoma in mice.

BACKGROUND: Treatment options for advanced intra-abdominal pediatric rhabdomyosarcoma (RMS) with peritoneal sarcomatosis (PS) include cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). However, optimal dosages and combination regimens of drugs used for HIPEC are underexplored. We aimed to evaluate the efficacy of HIPEC with cisplatin, doxorubicin, and their combination in vivo. METHODS: We established PS/RMS mouse model by intraperitoneally injecting RH30 cells into NOD/LtSz-scid IL2Rγ-null mice. Two weeks post xenotransplantation, mice underwent a single HIPEC procedure at 42°C for 60 minutes. Treatment groups received cisplatin (50, 100, and 150 mg/m2) and doxorubicin (30, 45, and 60 mg/m2), administered alone or combined. The control group underwent an intraperitoneal lavage with isotonic saline. Peritoneal cancer index (PCI) was used to quantify the extent of peritoneal tumor spread. Tissue samples were evaluated regarding proliferation (Ki-67) and apoptosis (caspase 3). RESULTS: Mice treated with cisplatin at 100 mg/m2 (PCI of 3.875, p = .007) and 150 mg/m2 (PCI of 4.556, p = .026), and doxorubicin at 30 mg/m2 (PCI of 2.875, p < .001) and 45 mg/m2 (PCI of 4.143, p = .021) showed reduced PCI, with the combination of cisplatin 50 mg/m2 and doxorubicin 30 mg/m2 showing the most prominent effect (PCI of 3.333, p < .001) compared to the control group (PCI of 8.615). Histologically, there was no difference in Ki-67 or caspase 3 expression among the groups. CONCLUSIONS: The cisplatin- and doxorubicin-based HIPEC significantly reduces peritoneal tumor dissemination in vivo. Further investigations are needed to explore the underlying molecular responses to optimize therapeutic strategies.