Peritoneal Spread Research Articles

The Extent of Tumor in the Peritoneum and Liver Influences Outcomes After Surgery for Synchronous Liver and Peritoneal Colorectal Metastases: A Cohort Study.

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRSH) or liver resection have led to increased survival in patients with peritoneal or liver metastases of colorectal cancer. Selected patients undergo concomitant CRSH and liver resection. Differences in survival and morbidity between patients who underwent concomitant surgery, CRSH or liver resection for peritoneal and/or liver metastases were compared. Patients who underwent liver resection and/or CRSH for colorectal liver and/or peritoneal metastases, 2006-2016, were included. Regression analysis was used to evaluate the associations between baseline characteristics and survival. Overall, 634 patients were studied. Twenty-eight patients had peritoneal and liver metastases, 121 patients had peritoneal metastases only, and 485 patients had isolated liver metastases. Median survival after concomitant treatment was 23.8months (95% CI 12.8-43.8), after CRSH 34.5months (95% CI 27.1-41.9), and after liver resection 54.2months (95% CI 47.4-61.0) (p < 0.001). Increased hepatic tumor burden (HR 3.2, 95% CI 1.8-5.8) and high-volume peritoneal disease (HR 6.0, 95% CI 3.7-9.8) were associated with decreased survival in multivariate analysis. Postoperative complications according to a Clavien-Dindo score > 3a were observed in 11% in the liver resection group, 15% in the CRSH group, and 11% in the concomitant treatment group (p = 0.945). Patients treated with concomitant surgery for liver and peritoneal metastases experienced a shorter median overall survival than patients treated for metastases at an isolated site but had a similar rate of severe postoperative complications. The extent of peritoneal spread seemed to impact survival more than the tumor burden in the liver.

HPB SO07 - Update to the role of staging laparoscopies in stratifying patients by operability in perihilar cholangiocarcinoma

Abstract Background Radical resection of perihilar cholangiocarcinoma (pCCA) is only an option for the minority presenting at an early stage. Sensitivity of radiological imaging to detect liver and peritoneal metastases is insufficient. Our published 2017 cohort study demonstrated over a quarter of patients with no radiologically detectable metastatic disease were subsequently found to have unresectable disease by staging laparoscopy. However, less than 3% of these patients had preoperative PET-CT, which is now strongly recommended in new national guidance.Advances in CT and MRI sensitivity and increased PET-CT use demanded a reassessment of the need for staging laparoscopy in diagnostic assessment of resectability. Method All patients referred to a tertiary UK hepatobiliary centre with a new diagnosis of radiologically suspected or biopsy-proven pCCA from January 2020 to January 2024 were included (n=305). Patients were identified through a prospectively maintained cancer database. Electronic health records were interrogated for demographic data, preoperative radiological imaging, and details related to operative procedures. Those referred with, or subsequently found to have, any of the following conditions were excluded: recurrent pCCA, intrahepatic or distal cholangiocarcinoma, gallbladder cancer or benign hepatobiliary disease. Results All patients underwent CT chest, abdomen and pelvis. 194 (64%) received contrast MRI liver or MRCP. Based on these, 242 (79%) had locally advanced or metastatic cancer, comorbidities precluding resection or otherwise declined surgery. PET-CT was employed to investigate all remaining 63 patients, which discovered metastatic disease in 16 patients (25%). 47 patients proceeded to staging laparoscopy. This yielded metastatic or locally advanced disease in five patients (11%); a near-statistically significant drop compared to our previously published yield of 27.2% (p=0.060). Two (5%) had open-and-close laparotomies for irresectable disease, compared to 16 of 114 (14%) in our 2017 publication (p=0.14). Conclusion Technological advances of CT and MRI and use of PET-CT have vastly improved detection of irresectable pCCA. This study reinforces the merits of PET-CT in identifying occult disease, and we would encourage units that undertake these resections to utilise this imaging modality prior to undertaking staging laparoscopy. Nevertheless, peritoneal spread remains challenging to exclude radiologically, and diagnostic laparoscopy endures as a vital tool in the prevention of open-and-close laparotomies.

Imaging of peritoneal metastases of ovarian and colorectal cancer: joint recommendations of ESGAR, ESUR, PSOGI, and EANM.

Diagnostic imaging of peritoneal metastases in ovarian and colorectal cancer remains pivotal in selecting the most appropriate treatment and balancing clinical benefit with treatment-related morbidity and mortality. To address the challenges related to diagnostic imaging and detecting and reporting peritoneal metastatic spread, a joint guideline was created by the European Society of Gastrointestinal and Abdominal Radiology (ESGAR), European Society of Urogenital Radiology (ESUR), Peritoneal Surface Oncology Group International (PSOGI), and European Association of Nuclear Medicine (EANM). A targeted literature search was performed and consensus recommendations were proposed using Delphi questionnaires and a five-point Likert scale. A total of three Delphi rounds were performed. Consensus was reached on the position of diagnostic imaging for assessment of operability, treatment response monitoring, and follow-up of peritoneal metastases, optimal imaging modality and their technical imaging requirements depending on the indication and how to optimise communication of imaging results by the report and multidisciplinary board discussion. The complete list of recommendations is provided. These expert consensus statements aim to guide appropriate indications, acquisition, interpretation, and reporting of imaging for operability assessment, treatment response monitoring, and follow-up of peritoneal metastases in ovarian and colorectal cancer patients. Question Staging peritoneal metastases (PM) helps toguide clinical decision-making for colorectal and ovarian cancer patients. How can we optimise the use of imaging techniques to assess PM? Findings Imaging plays a crucial role in the detection, operability assessment, treatment response monitoring, and follow-up of peritoneal metastases in colorectal and ovarian cancer patients. Clinical relevance These expert consensus statements aim to guide appropriate indication, acquisition, interpretation, and reporting of imaging for operability assessment, treatment response monitoring, and follow-up of peritoneal metastases in ovarian and colorectal cancer patients.

Ten Hypermethylated lncRNA Genes Are Specifically Involved in the Initiation, Progression, and Lymphatic and Peritoneal Metastasis of Epithelial Ovarian Cancer.

Our work aimed to evaluate and differentiate the role of ten lncRNA genes (GAS5, HAND2-AS1, KCNK15-AS1, MAGI2-AS3, MEG3, SEMA3B-AS1, SNHG6, SSTR5-AS1, ZEB1-AS1, and ZNF667-AS1) in the development and progression of epithelial ovarian cancer (EOC). A representative set of clinical samples was used: 140 primary tumors from patients without and with metastases and 59 peritoneal metastases. Using MS-qPCR, we demonstrated an increase in methylation levels of all ten lncRNA genes in tumors compared to normal tissues (p < 0.001). Using RT-qPCR, we showed downregulation and an inverse relationship between methylation and expression levels for ten lncRNAs (rs < -0.5). We further identified lncRNA genes that were specifically hypermethylated in tumors from patients with metastases to lymph nodes (HAND2-AS1), peritoneum (KCNK15-AS1, MEG3, and SEMA3B-AS1), and greater omentum (MEG3, SEMA3B-AS1, and ZNF667-AS1). The same four lncRNA genes involved in peritoneal spread were associated with clinical stage and tumor extent (p < 0.001). Interestingly, we found a reversion from increase to decrease in the hypermethylation level of five metastasis-related lncRNA genes (MEG3, SEMA3B-AS1, SSTR5-AS1, ZEB1-AS1, and ZNF667-AS1) in 59 peritoneal metastases. This reversion may be associated with partial epithelial-mesenchymal transition (EMT) in metastatic cells, as indicated by a decrease in the level of the EMT marker, CDH1 mRNA (p < 0.01). Furthermore, novel mRNA targets and regulated miRNAs were predicted for a number of the studied lncRNAs using the NCBI GEO datasets and analyzed by RT-qPCR and transfection of SKOV3 and OVCAR3 cells. In addition, hypermethylation of SEMA3B-AS1, SSTR5-AS1, and ZNF667-AS1 genes was proposed as a marker for overall survival in patients with EOC.

Epithelial splicing regulatory protein 1 promotes peritoneal dissemination of ovarian cancer by inducing the formation of circular RNAs modulating epithelial plasticity

Peritoneal metastases prevalently occur in ovarian cancer, deteriorating patient prognosis. During the metastatic cascade, tumor plasticity enables cells to adapt to environmental changes, thereby facilitating dissemination. We previously found that epithelial splicing regulatory protein 1 (ESRP1) is linked to peritoneal metastasis and epithelial-mesenchymal plasticity in ovarian cancer. This study delves into the underlying mechanism. We found that ESRP1 preserves epithelial plasticity in ovarian cancer cells in vitro and in vivo. Functionally, ESRP1 enhances ovarian cancer cell growth and peritoneal dissemination. High-throughput sequencing revealed several ESRP1-related epithelial RNAs, encompassing both linear and circular forms. Specifically, ESRP1 triggers the cyclization of circPAFAH1B2 and circUBAP2 through binding to the GGU sequences in adjacent introns. The two ESRP1-induced circular RNAs stabilize DKK3 and AHR mRNAs, which are critical for epithelial plasticity, through interaction with IGF2BP2. Collectively, ESRP1 triggers the formation of circPAFAH1B2 and circUBAP2, which in turn stabilizes DKK3 and AHR through IGF2BP2 binding, thereby modulating the epithelial plasticity and aiding the peritoneal spread of ovarian cancer cells. The findings unveiled a biological network, orchestrated by ESRP1, that governs the epithelial-mesenchymal plasticity of ovarian cancer cells, emphasizing the therapeutic potential of ESRP1 and its induced circular RNAs for ovarian cancer treatment.

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.

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. 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 60minutes. Treatment groups received cisplatin (50, 100, and 150mg/m2) and doxorubicin (30, 45, and 60mg/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). Mice treated with cisplatin at 100mg/m2 (PCI of 3.875, p=.007) and 150mg/m2 (PCI of 4.556, p=.026), and doxorubicin at 30mg/m2 (PCI of 2.875, p<.001) and 45mg/m2 (PCI of 4.143, p=.021) showed reduced PCI, with the combination of cisplatin 50mg/m2 and doxorubicin 30mg/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. 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.

Appendiceal adenocarcinoma-patterns of tumor spread and prognosis

IntroductionAppendiceal adenocarcinoma represents a diagnostic and therapeutic challenge since it is prone to early lymphatic and peritoneal spread. We aimed to analyze the proportion of lymph node metastases in completion right hemicolectomy specimens, risk factors for peritoneal metastases (PM), and prognosis after definitive treatment. MethodsNinety-three patients with appendiceal adenocarcinoma scheduled for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS + HIPEC) in Uppsala 2004–2020 were identified from a prospectively maintained registry. Risk factors for PM were assessed based on the presence (CT + group, n = 55) or absence (CT – group, n = 37) of visible PM at baseline CT scan. Prognostic factors were analyzed based on the actual presence (PM group, n = 66) or absence (no PM group, n = 27) of PM. ResultsThe median age was 60 (26–78). Forty-eight patients were women. Resection of PM at initial surgery indicated an 80 % risk of finding PM at a follow-up exploration. R1 appendectomy and perforated appendix had a similar risk for PM (24 %,26 %) which increased to 38 % if both were present.Regional lymph node metastases occurred in 31 % in the CT + group vs. 14 % in the CT − group (p = 0.005) and was associated with poor survival HR 5.16 (1.49–17.81).The 5-year OS and DFS rates were 54 % and 29 % in the PM group. ConclusionsPatients with certain risk factors have a high likelihood of PM despite a normal CT scan, which justifies selective exploration at a HIPEC center. Regional lymph node spread supports the current practice of completion right hemicolectomy and is a significant prognostic factor.

Profiling of metabolic dysregulation in ovarian cancer tissues and biofluids

Ovarian cancer (OC) is the most lethal gynecologic cancer, mainly due to late diagnosis with widespread peritoneal spread at first presentation. We performed metabolomic analyses of ovarian and paired control tissues using capillary electrophoresis-mass spectrometry and liquid chromatography-mass spectrometry to understand its metabolomic dysregulation. Of the 130 quantified metabolites, 96 metabolites of glycometabolism, including glycolysis, tricarboxylic acid cycles, urea cycles, and one-carbon metabolites, showed significant differences between the samples. To evaluate the local and systemic metabolomic differences in OC, we also analyzed low or non-invasively available biofluids, including plasma, urine, and saliva collected from patients with OC and benign gynecological diseases. All biofluids and tissue samples showed consistently elevated concentrations of N1,N12-diacetylspermine compared to controls. Four metabolites, polyamines, and betaine, were significantly and consistently elevated in both plasma and tissue samples. These data indicate that plasma metabolic dysregulation, which the most reflected by those of OC tissues. Our metabolomic profiles contribute to our understanding of metabolomic abnormalities in OC and their effects on biofluids.

Unusual Scenario: Ipsilateral Pelvic Lymph Node Metastasis in High- Grade Serous Ovarian Carcinoma without Peritoneal Extension - A Case Report

Introduction:: Ovarian cancers are the third most common gynecological cancers worldwide with serous carcinomas being the most common subtype with 90% of them as high-grade carcinomas. Case Presentation:: In the present case report a 60 years postmenopausal, nulliparous woman presented with complaints of bleeding per vaginum for 1-2 months with a left-sided solid-cystic ovarian mass of size 4x5 cm and ipsilateral enlarged external iliac and obturator lymph nodes which were diagnosed on histopathological examination as high-grade serous ovarian carcinoma (HGSOCs) with ipsilateral pelvic lymph node metastasis in presence of intact ovarian capsule and no metastatic deposits over the uterus, contralateral ovary and fallopian tubes, omentum, or any other gross peritoneal deposits. There was coexisting non-atypical endometrial hyperplasia. The patient was managed successfully with staging laparotomy with modified radical hysterectomy, and bilateral pelvic lymphadenectomy followed by six cycles of adjuvant chemotherapy with Paclitaxel and Carboplatin injections. Conclusion:: Patients with HGSOCs can have varied presentations with unusual involvement of lymph nodes in the absence of peritoneal spread. Hence, the clinician must be aware of these unusual presentations for the successful management of such cases.

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.

CT and MRI features of sarcomatoid urothelial carcinoma of the bladder and its differential diagnosis with conventional urothelial carcinoma

BackgroundSarcomatoid urothelial carcinoma (SUC) is a rare and highly malignant form of bladder cancer with a poor prognosis. Currently, there is limited information on the imaging features of bladder SUC and reliable indicators for distinguishing it from conventional urothelial carcinoma (CUC). The objective of our study was to identify the unique imaging characteristics of bladder SUC and determine factors that aid in its differential diagnosis.Materials and methodsThis retrospective study enrolled 22 participants with bladder SUC and 61 participants with CUC. The clinical, pathologic, and CT/MRI data from both groups were recorded, and a comparison was conducted using univariate analysis and multinomial logistic regression for distinguishing SUC from CUC.ResultsThe majority of SUCs were located in the trigone of the bladder and exhibited large tumor size, irregular shape, low ADC values, Vesical Imaging-Reporting and Data System (VI-RADS) score ≥ 4, the presence of necrosis, and an invasive nature. Univariate analysis revealed significant differences in terms of tumor location, shape, the maximum long-axis diameter (LAD), the short-axis diameter (SAD), ADC-value, VI-RADS scores, necrosis, extravesical extension (EVE), pelvic peritoneal spread (PPS), and hydronephrosis/ureteral effusion (p < .001 ~ p = .037) between SUCs and CUCs. Multinomial logistic regression found that only SAD (p = .014) and necrosis (p = .003) emerged as independent predictors for differentiating between SUC and CUC. The model based on these two factors achieved an area under curve (AUC) of 0.849 in ROC curve analysis.ConclusionBladder SUC demonstrates several distinct imaging features, including a high incidence of trigone involvement, large tumor size, and obvious invasiveness accompanied by necrosis. A bladder tumor with a large SAD and evidence of necrosis is more likely to be SUC rather than CUC.

Comparison of Peritoneal Cytology Results Before and After Resection in Gastric Cancer Patients.

Peritoneal cytology is used to detect the peritoneal spread of gastric cancer and to assess survival rate. The aim of this study was to compare the risk factors, recurrence, and survival of gastric cancer patients with positive and negative peritoneal cytology before and after resection. Patients with gastric cancer who underwent elective surgery were retrospectively analysed. The study covered a period between September 2018 and September 2020. After applying the exclusion criteria, 57 patients were included in the study. For the purpose of this study, peritoneal cytology was taken from the same three intra-abdominal regions before and after resection from patients with operable gastric cancer. Of the 57 patients included in the study, 36 (63.2%) were male patients and 21 (36.8%) were female patients. Preoperative or postoperative malignant cytology was detected in 12 patients (21.1%). Tumour diameter was larger in patients with preoperatively detected malignant cytology than in the patients with postoperatively positive malignant cytology (66.67 mm vs. 44.44 mm) (p = 0.006). The recurrence rate was higher in patients with preoperative and postoperative positive cytology than in those with negative cytology (p = 0.019). The survival of patients with preoperative malignant cytology was worse than the survival of patients with preoperative benign cytology (p = 0.011). A significant correlation was found between lymphovascular invasion (+), perineural invasion (+), T4, Stage 3 disease, number of malignant lymph nodes, and preoperative cytology positivity (p <0.05). In our study, we found that the preoperative cytology positivity is associated with lymphovascular invasion positivity, perineural invasion positivity, T4 tumour, Stage 3 disease, and the number of malignant lymph nodes. Postoperative positive cytology was not associated with the same variables. Because of the significant associations in preoperative positivity, fluid samples should be obtained immediately after the abdomen is open and before the tumour is manipulated. If possible, fluid samples should be taken from different quadrants, but if the sample is to be taken from a single quadrant, it should be taken from the pelvis.

Detection of Carcinoma-Associated Fibroblasts Derived from Mesothelial Cells via Mesothelial-to-Mesenchymal Transition in Primary Ovarian Carcinomas.

Carcinoma-associated fibroblasts (CAFs) are highly accumulated in the tumor-surrounding stroma of primary epithelial ovarian cancer (OC). CAFs exert important functions for the vascularization, growth, and progression of OC cells. However, the origin of CAFs in primary OC had not yet been studied, and they were assumed to arise from the activation of resident fibroblasts. Here, we compared CAFs in the ovary to CAFs found in peritoneal metastases from patients with advanced OC. Our findings show that CAFs from primary tumors and peritoneal metastases share the expression of mesothelial markers. Therefore, similar to peritoneal carcinomatosis, CAFs in primary ovarian carcinomas may originate from mesothelial cells via a mesothelial-to-mesenchymal transition. The detection of mesothelial-derived CAFs in tumors confined to the ovary and identification of biomarkers could be the key to the early detection of OC and peritoneal spread.

Enhancing precision in colorectal cancer surgery: development of an LGR5-targeting RSPO1 peptide mimetic as a contrast agent for intraoperative fluorescence molecular imaging

ABSTRACT Colorectal cancer (CRC) is the third most common cancer worldwide. In the United States alone, CRC was responsible for approximately 52,550 deaths in 2023, with an estimated 153,020 new cases. CRC presents with synchronous peritoneal spread in 5–10% of patients, and up to 20–50% of patients with recurrent disease will develop metachronous colorectal cancer peritoneal metastatic (CRC-PM) disease. Eradication of the tumor, tumor margins and microscopic residual disease is paramount, as microscopic residual disease is associated with local recurrences, with 5-year survival rates of less than 35%. The success of resection and reduction of residual disease depends on the accuracy with which cancer cells and normal tissue can be intra-operatively distinguished. Fluorescence Molecular Imaging (IFMI) and tumor-targeted contrast agents represent a promising approach for intraoperative detection and surgical intervention. Proper target selection, the development of scalable imaging agents and enhanced real-time tumor and tumor microenvironment imaging are critical to enabling enhanced surgical resection. LGR5 (leucine-rich repeat-containing G-protein-coupled receptor 5), a colonic crypt stem cell marker and the receptor for the R-spondins (RSPO) in the Wnt signaling pathway, is also expressed on colorectal cancer stem cells (CSC) and on CRC tumors and metastases, suggesting it could be a useful target for imaging of CRC. However, there are numerous diverging reports on the role of LGR5 in CRC therapy and outcomes. Herein, we report on the synthesis and validation of a 37 amino acid RSPO1-mimetic peptide, termed RC18, that was specifically designed to access the R-spondin binding site of LGR5 to potentially be used for interoperative imaging of CRC-PM. The receptor-binding capabilities of the RC18 indicate that direct interactions with LGR5 neither significantly increased LGR5 signaling nor blocked RSPO1 binding and signal transduction, suggesting that the RSPO1-mimetic is functionally inert, making it an attractive contrast agent for intraoperative CRC-PM imaging.

PLAG1-Rearranged Uterine Sarcomas: A Study of 11 Cases Showing a Wide Phenotypical Spectrum Not Limited to Myxoid Leiomyosarcoma-Like Morphology

PLAG1 gene fusions were recently identified in a subset of uterine myxoid leiomyosarcomas (M-LMS). However, we have encountered cases of PLAG1-rearranged uterine sarcomas lacking M-LMS-like morphology and/or any expression of smooth muscle markers. To better characterize their clinicopathologic features, we performed a multiinstitutional search that yielded 11 cases. The patients ranged in age from 34 to 72 years (mean, 57 years). All tumors arose in the uterine corpus, ranging in size from 6.5 to 32 cm (mean, 15 cm). The most common stage at presentation was pT1b (n = 6), and 3 cases had stage pT1 (unspecified), and 1 case each presented in stages pT2a and pT3b. Most were treated only with hysterectomy and adnexectomy. The follow-up (range, 7-71 months; median, 39 months) was available for 7 patients. Three cases (7-21 months of follow-up) had no evidence of disease. Three of the 4 remaining patients died of disease within 55 to 71 months, while peritoneal spread developed in the last patient, and the patient was transferred for palliative care at 39 months. Morphologically, the tumors showed a high intertumoral and intratumoral heterogeneity. M-LMS-like and epithelioid leiomyosarcoma–like morphology were present in 3 and 5 primary tumors, respectively, the remaining mostly presented as nondescript ovoid or spindle cell sarcomas. Unusual morphologic findings included prominently hyalinized stroma (n = 3), adipocytic differentiation with areas mimicking myxoid liposarcoma (n = 2), osteosarcomatous differentiation (n = 1), and undifferentiated pleomorphic sarcoma–like areas (n = 1). The mitotic activity ranged from 3 to 24 mitoses per 10 high-power fields (mean, 9); 3 of 10 cases showed necrosis. In 3 of 11 cases, no expression of smooth muscle actin, h-caldesmon, or desmin was noted, whereas 5 of 5 cases expressed PLAG1. By RNA sequencing, the following fusion partners were identified: PUM1, CHCHD7 (each n = 2), C15orf29, CD44, MYOCD, FRMD6, PTK2, and TRPS1 (each n = 1). One case only showed PLAG1 gene break by fluorescence in situ hybridization. Our study documents a much broader morphologic spectrum of PLAG1-rearranged uterine sarcomas than previously reported, encompassing but not limited to M-LMS-like morphology with occasional heterologous (particularly adipocytic) differentiation. As it is currently difficult to precisely define their line of differentiation, for the time being, we suggest using a descriptive name “PLAG1-rearranged uterine sarcoma.”

Stratification of Homologous Recombination Deficiency-Negative High-Grade Ovarian Cancer by the Type of Peritoneal Spread into Two Groups with Distinct Survival Outcomes.

Homologous recombination deficiency (HRD) has evolved into a major diagnostic marker in high-grade ovarian cancer (HGOC), predicting the response to poly (adenosine diphosphate-ribose) polymerase inhibitors (PARPi) and also platinum-based therapy. In addition to HRD, the type of peritoneal tumor spread influences the treatment response and patient survival; miliary type tumor spread has a poorer predicted outcome than non-miliary type tumor spread. Known methods for HRD assessment were adapted for our technical requirements and the predictive-value integrated genomic instability score (PIGIS) for HRD assessment evolved as an outcome. PIGIS was validated in HGOC samples from 122 patients. We used PIGIS to analyze whether the type of tumor spread correlated with HRD status and whether this had an impact on survival. We demonstrated that PIGIS can discriminate HRD-positive from HRD-negative samples. Tumors with a miliary tumor spread are HRD-negative and have a very bad prognosis with a progression-free survival (PFS) of 15.6 months and an overall survival (OS) of 3.9 years. However, HRD-negative non-miliary spreading tumors in our cohort had a much better prognosis (PFS 35.4 months, OS 8.9 years); similar to HRD-positive tumors (PFS 34.7 months, OS 8.9 years). Our results indicate that in a predominantly PARPi naïve cohort, the type of tumor spread and concomitant cytoreduction efficiency is a better predictor of survival than HRD and that HRD may be an accidental surrogate marker for tumor spread and concomitant cytoreduction efficiency. It remains to be determined whether this also applies for sensitivity to PARPi.

Focus on human epidermal growth factor receptor 2 (HER2) positive metastatic colorectal cancer (HER2+ mCRC): A real world retrospective analysis.

3080 Background: HER2+ mCRCs, displaying HER2 overexpression or ERBB2 amplification, represent a rare molecular subset, accounting for 2- 6% of all mCRCs. HER2+ mCRCs are thought to be enriched in KRASwt pts and associated with distal primary tumor location. While its prognostic value is debated, HER2 seems a negative predictor for antiEGFR agents. Recently, its role as a potential actionable target has emerged, with promising results in refractory mCRC. Despite that, nowadays HER2 testing is not routinely included in the diagnostic workup of mCRC. Methods: This is an observational, retrospective, multicenter study, aiming to investigate and describe clinical and molecular features and prognostic value of HER2+ mCRCs from real world pts. Pts with mCRC tested for HER2 status who received at least one line of therapy (tx) at 11 Italian Institutions within the Lazio Region between Mar2011 and Jan2024 were enrolled. HER2 status was assessed either for HER2 overexpression using IHC according to the HERACLES diagnostic criteria or for ERBB2 amplification using NGS, followed by IHC confirmation for positive cases. Differences between groups for categorical variables were compared using the Chi Square test. Endpoint for prognostic assessment was OS, estimated with the Kaplan-Meier method and compared using log-rank test. Endpoints for predictive assessment were RR and DCR. Statistical significance was set at p .05. Results: 422 pts were included, of those 38 pts had a HER2+ mCRC (9%). HER2 positivity was more frequent among patients with RASwt tumor compared to RASmt (12.2 vs 6.1%; p .029), lung metastasis ( p .013) and synchronous metastatic disease ( p .044). No correlation with age, sex, primary tumor location, peritoneal spread, histologic grading and mucinous histology was observed. At a median FU of 19 months, OS was significantly shorter in HER2+ compared to HER2- mCRCs (HR 2.17, 95%CI 1.14-4.13; p .017). 104 pts with RASwt mCRC received an antiEGFR-based first line tx and were evaluable for response; of those 96 were HER2- and 12 HER2+. RR was higher for HER2- tumors (80 vs 42%; p .003), while no difference was observed for DCR (96 vs 83%; p .085). Of 38 HER2+ tumors, 14 received an antiHER2 tx, of those 11 were RASwt and 3 RASmt. RAS status did not impact on antiHER2 activity (DCR 64 vs 33% for RASwt and RASmt; p .347). Conclusions: We showed that HER2+ mCRCs are more frequently, although not exclusively, RASwt, display a lung tropism, present with synchronous metastases and have a negative prognosis. Moreover, in accordance with results from DESTINY-CRC02, the target actionability seems to be retained irrespective of RAS status. Given also the possible use in first line of antiHER2 tx in the near future, the baseline molecular diagnostic workup of mCRC must include HER2 status assessment, irrespective of RAS mutational status and primary tumor location.

The role of Piezo1 mechanotransduction in high-grade serous ovarian cancer: Insights from an in vitro model of collective detachment.

Slowing peritoneal spread in high-grade serous ovarian cancer (HGSOC) would improve patient prognosis and quality of life. HGSOC spreads when single cells and spheroids detach, float through the peritoneal fluid and take over new sites, with spheroids thought to be more aggressive than single cells. Using our in vitro model of spheroid collective detachment, we determine that increased substrate stiffness led to the detachment of more spheroids. We identified a mechanism where Piezo1 activity increased MMP-1/MMP-10, decreased collagen I and fibronectin, and increased spheroid detachment. Piezo1 expression was confirmed in omental masses from patients with stage III/IV HGSOC. Using OV90 and CRISPR-modified PIEZO1-/- OV90 in a mouse xenograft model, we determined that while both genotypes efficiently took over the omentum, loss of Piezo1 significantly decreased ascitic volume, tumor spheroids in the ascites, and the number of macroscopic tumors in the mesentery. These results support that slowing collective detachment may benefit patients and identify Piezo1 as a potential therapeutic target.

Oncolytic adenovirus in treating malignant ascites: A phase II trial and longitudinal single-cell study

Malignant ascites is a common complication resulting from the peritoneal spread of malignancies, and currently lacks effective treatments. We conducted a phase II trial (NCT04771676) to investigate the efficacy and safety of oncolytic adenovirus H101 and virotherapy-induced immune response in 25 patients with malignant ascites. Oncolytic virotherapy achieved an increased median time to repeat paracentesis of 45 days (95% confidence interval 16.5–73.5 days), compared to the preset control value of 13 days. Therapy was well-tolerated, with pyrexia, fatigue, nausea, and abdominal pain as the most common toxicities. Longitudinal single-cell profiling identified marked oncolysis, early virus replication, and enhanced CD8+ T cells-macrophages immune checkpoint crosstalk, especially in responsive patients. H101 also triggered a proliferative burst of CXCR6+ and GZMK+CD8+ T cells with promoted tumor-specific cytotoxicity. Further establishment of oncolytic virus-induced T cell expansion signature (OiTE) implicated the potential benefits for H101-responsive patients from subsequent anti-PD(L)1 therapy. Patients with up-regulated immune-signaling pathways in tumor cells and a higher proportion of CLEC10A+ DCs and GZMK+CD8+ T cells at baseline showed a superior response to H101 treatment. Our study demonstrates promising clinical responses and tolerability of oncolytic adenovirus in treating malignant ascites and provided insights into the relevant cellular processes following oncolytic virotherapy.

Pathophysiology of peritoneal colorectal metastases

Colorectal cancer (CRC) disseminates through three routes; the lymphatic, the haematogenous, and the transcoelomic, which leads to the development of peritoneal carcinomatosis (PC). PC is associated with a poor prognosis and bad quality of life. A loco-regional treatment strategy for PC combining cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) has demonstrated promising clinical results. The comprehension of the molecular events of peritoneal disease spread is of the utmost importance for many reasons. The emergence of PC is the result of a molecular crosstalk between cancer cells and host elements, involving several well-defined steps together known as the peritoneal metastatic cascade. Individual or clumps of tumour cells detach from the primary tumour, gain access to the peritoneal cavity and become susceptible to the regular peritoneal transport. They attach to the distant peritoneum, subsequently invade the subperitoneal space, where angiogenesis sustains proliferation and enables further metastatic growth. These molecular events make up a continuous and interdependent process. The present publication reviews the current data regarding the molecular mechanisms underlying the development of colorectal PC, with a special focus on the peritoneum.