Peritoneal Carcinomatosis Patients Research Articles

The Potential Prognostic Impact of Associated Peritoneal Carcinomatosis in Patients with Stage II and III Epithelial Ovarian Cancer Who Had Upfront Complete Cytoreduction

The Potential Prognostic Impact of Associated Peritoneal Carcinomatosis in Patients with Stage II and III Epithelial Ovarian Cancer Who Had Upfront Complete Cytoreduction

Prognostic role of body composition in peritoneal carcinomatosis patients undergoing cytoreduction and hyperthermic intraperitoneal chemotherapy

BackgroundBioelectric impedance analysis (BIA)-measured body composition and nutritional status have been used as prognostic indicators in various cancer cohorts. This study investigated whether BIA could provide information on prognosis in peritoneal carcinomatosis patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC).MethodsWe retrospectively analyzed the data of 99 patients with preoperative BIA data among those who underwent CRS and HIPEC. The association between BIA-derived parameters and intraoperative peritoneal cancer index (PCI) score was assessed. Predictive analysis for the occurrence of postoperative morbidities including major complications (Clavien–Dindo classification 3–4) and re-admission within 30 days after surgery as well as 1 year mortality was also performed.ResultsBIA-derived mineral (r = 0.224, p = 0.027), fat (r = − 0.202, p = 0.048), and total body water (TBW)/fat-free mass (FFM) (r = − 0.280, p = 0.005) showed significant associations with intraoperative PCI score. Lower TBW/FFM was an independent predictor of major postoperative complications (OR 0.047, 95% CI 0.003–0.749, p = 0.031) and re-admission (OR 0.094, 95% CI 0.014–0.657, p = 0.017) within 30 days after surgery. Higher fat mass was also independently associated with a higher risk of major postoperative complications (OR 1.120, 95% CI 1.006–1.248, p = 0.039) and re-admission (OR 1.123, 95% CI 1.024–1.230, p = 0.013). Intraoperative PCI score > 20 (OR 4.489, 95% CI 1.191–16.917, p = 0.027) and re-admission within 30 days after surgery (OR 5.269, 95% CI 1.288–21.547, p = 0.021) independently predicted postoperative 1-year mortality.ConclusionsWe demonstrate that preoperative BIA-derived TBW/FFM and fat mass were significantly correlated with metastatic extent, assessed by PCI score, in patients with peritoneal carcinomatosis. In addition, BIA-derived TBW/FFM and fat mass showed independent predictability for postoperative 30-day major complications and re-admission in patients undergoing CRS and HIPEC. Our findings suggest that assessment of BIA may improve discrete risk stratification in patients who are planned to receive CRS and HIPEC.

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

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. 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. 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 ≥ 60years (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. 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.

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

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

Diagnostic value of positron emission tomography/computed tomography (PET/CT) in detection of peritoneal carcinomatosis

BackgroundThe diagnosis of peritoneal carcinomatosis is challenging and can be difficult to detect with imaging, especially the detection of small-sized peritoneal lesions. The presence of peritoneal neoplastic spread alters tumour staging and is one of the most significant prognostic indicators in several malignancies, and the purpose of this study was to highlight the diagnostic value of PET/CT in detection of peritoneal carcinomatosis in patients with malignant neoplastic disease.ResultsPET/CT has 76.2% sensitivity, 88.9% specificity, 94.1% PPV, 61.5% NPV and 80% accuracy in detection of peritoneal carcinomatosis. Different patterns of FDG uptake of peritoneal carcinomatosis were found such as focal nodular uptake, diffuse abdominal uptake and liver surface focal or diffuse uptake. From all these different patterns, focal nodular uptake was the most frequent pattern. The best cut-off value of SUVmax was 5 for diagnosis.ConclusionsThe study affirms the significant role of PET/CT in the diagnosis of peritoneal carcinomatosis and its important value in the staging, management and follow-up of patients with secondary peritoneal malignancies, especially in case of unavailable or inappropriate peritoneal biopsy. Therefore, PET/CT could help reduce the number of laparotomies and a better selection of patients who are candidates for adjuvant chemotherapy.

Hyperthermic Intraperitoneal Chemotherapy Following Cytoreductive Surgery for Colorectal Peritoneal Carcinomatosis Patients: A Review.

Colorectal peritoneal carcinomatosis (CPC) is an advanced malignancy and is typically associated with a poor prognosis. Hyperthermic intraperitoneal chemotherapy (HIPEC) following complete cytoreductive surgery (CRS) is a novel, advanced loco-regional treatment for colorectal cancer that is currently being used to treat peritoneal carcinomatosis (PC). The present review aims to describe the evidence-based literature on the efficacy and safety of this treatment approach in patients with PC originating from colorectal cancer and to summarize its complications. All published literature regarding the efficacy of HIPEC for the treatment of CPC was reviewed; 16 studies were included in this paper. The overall survival rate for the HIPEC group ranged from 63% to 93%. The overall median survival for the HIPEC and non-HIPEC groups ranged from 13 to 60.1 months and 12.6 to 41.2 months, respectively. The overall median survival of patients in the HIPEC group was comparatively better than those in the non-HIPEC group. There was insufficient evidence to suggest whether this treatment regimen was associated with a high or low morbidity rate in comparison to other groups. However, the mortality rate associated with this treatment regimen was low. In conclusion, the present data provide insufficient evidence regarding the beneficial effects of using HIPEC following CRS treatment. Therefore, further studies are required to determine the benefits of HIPEC for CPC patients.

Peritoneal carcinomatosis after minimally invasive surgery versus open radical hysterectomy: systematic review and meta-analysis

ObjectiveTo assess the incidence of peritoneal carcinomatosis in patients undergoing minimally invasive or open radical hysterectomy for cervical cancer.MethodsThe MEDLINE (accessed through Ovid), Embase, Cochrane Central Register of Controlled Trials...

Spectral CT in peritoneal carcinomatosis from ovarian cancer: a tool for differential diagnosis of small nodules?

The detection of peritoneal carcinomatosis in patients with ovarian cancer is crucial to establish the correct therapeutic planning (debulking surgery versus neoadjuvant chemotherapy).Often, however, the nodules of peritoneal carcinomatosis are very small in size or have a reticular appearance that can mimic the fat stranding that is typical of acute inflammation conditions. Our hypothesis is that the use of dual-layer spectral computed tomography with its applications, such as virtual monoenergetic imaging and Z-effective imaging, might improve the detection and the characterisation of peritoneal nodules, increasing sensitivity and diagnostic accuracy, as recently described for other oncological diseases.

The Prediction of Peritoneal Carcinomatosis in Patients with Colorectal Cancer Using Machine Learning.

The incidence of colon, rectal, and colorectal cancer is very high, and diagnosis is often made in the advanced stages of the disease. In cases where peritoneal carcinomatosis is limited, patients can benefit from newer treatment options if the disease is promptly identified, and they are referred to specialized centers. Therefore, an essential diagnostic benefit would be identifying those factors that could lead to early diagnosis. A retrospective study was performed using patient data gathered from 2010 to 2020. The collected data were represented by routine blood tests subjected to stringent inclusion and exclusion criteria. In order to determine the presence or absence of peritoneal carcinomatosis in colorectal cancer patients, three types of machine learning approaches were applied: a neuro-evolutive methodology based on artificial neural network (ANN), support vector machines (SVM), and random forests (RF), all combined with differential evolution (DE). The optimizer (DE in our case) determined the internal and structural parameters that defined the ANN, SVM, and RF in their optimal form. The RF strategy obtained the best accuracy in the testing phase (0.75). Using this RF model, a sensitivity analysis was applied to determine the influence of each parameter on the presence or absence of peritoneal carcinomatosis.

A comparative population-based analysis of peritoneal carcinomatosis in patients undergoing robotic-assisted and open radical cystectomy.

To compare the population-based incidence of peritoneal carcinomatosis following open (ORC) vs. robotic-assisted radical cystectomy (RARC). Using the Surveillance, Epidemiology and End Results Program (SEER)-Medicare linked data, we identified 1,621 patients who underwent radical cystectomy for bladder cancer during 2009 and 2014; 18.1% (n = 294) and 81.9% (n = 1327) underwent RARC and ORC, respectively. We subsequently evaluated the rates of peritoneal carcinomatosis at 6, 12, and 24 months following surgery. Multivariable proportional hazards regression was performed to determine factors associated with development of peritoneal carcinomatosis. Patients who underwent RARC vs. ORC were more likely to be male (p = 0.04); however, age at diagnosis, race, comorbidities, education, and marital status (all p > 0.05) did not differ by surgical approaches. Our findings showed that there were no significant differences in the rates of peritoneal carcinomatosis between ORC and RARC at 6, 12, and 24 months. In adjusted analyses, factors associated with peritoneal carcinomatosis were advanced N stage (N0 versus N2/3: HR 0.30, 95% CI 0.16-0.55, p < 0.01), preoperative hydronephrosis (HR 1.70, 95% CI 1.09-2.65, p = 0.04), higher T stage (T1 versus T4: HR 0.34, 95% CI 0.15-0.79, p < 0.01; T2 versus T4: HR 0.39, 95% CI 0.20-0.76, p < 0.01), and use of neoadjuvant chemotherapy (HR 1.78, 95% CI 1.11-2.84, p < 0.01). However, RARC was not associated with peritoneal carcinomatosis (HR 1.36, 95% CI 0.78-2.35). In this population-based analysis, we found no difference in peritoneal carcinomatosis between robotic or open approaches to radical cystectomy. These data should be reassuring to those utilizing robotic cystectomy.

Can baseline quality of life scores predict for morbidity and survival after CRS and HIPEC: a prospective study of 151 patients.

ObjectivesVarious studies have shown that good quality of life (QoL) can be achieved after cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). There is prognostic value of baseline QoL in post-operative outcome in Western setting. Our prospective study aims to validate these observations and elucidate clinical factors that predict poorer QoL in Asian peritoneal carcinomatosis patients.MethodsEuropean Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire was administered to patients before CRS and HIPEC and thereafter at 3, 6 and 12 months.ResultsA total of 151 patients underwent 155 surgeries. Four hundred and seventy two questionnaires were completed. Median disease-free survival (DFS) was 16.5 months. Three year DFS and overall survival (OS) were 24.0% and 73.0% respectively. Post-operative global health status significantly increased at 3, 6 and 12 months. The decreases in functional scales recovered to baseline by 1-year post-surgery. Peritoneal carcinomatosis index (PCI), presence of stoma, peritonectomy duration, death within one year, post-operative complication and length of SICU stay negatively influenced QoL. Complication rates were higher in patients with lower global health status, physical and role functioning scores and higher symptom summary scores at baseline. Lower social functioning score, and higher pain, dyspnoea and symptom summary scores at baseline were significantly associated with poorer OS.ConclusionsVarious clinical factors can help us predict a patient’s QoL after surgery. Several baseline factors were also able to predict morbidity and survival. Going forward, we can use these factors to help us better select patients who will have a greater benefit from CRS and HIPEC.

Occurrence of peritoneal carcinomatosis in patients with rectal cancer undergoing staging pelvic MRI: clinical observations.

Describe the cumulative incidence (CUIN) of peritoneal carcinomatosis (PC) and survival in patients presenting with advanced rectal cancer at staging pelvic MRI. From 2013 to 2018, clinicopathologic records of patients with pretreatment rectal MRI clinical (c)T3c, cT3d, cT4a, and cT4b primary rectal adenocarcinoma were retrospectively reviewed by two radiologists. Standard MRI descriptors and pathologic stages were recorded. Recurrence-free (RFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Development of PC was explored using competing risk analysis. Differences in survival were compared using the log-rank test. Gray's test was used to test for differences in CUIN of PC. Three hundred forty-three patients (147 women; median age, 56 years) had MRI stages cT3cd, n = 170; cT4a, n = 40; and cT4b, n = 133. Median follow-up among survivors was 27 months (0.36-70 months). For M1 patients, OS differed only by cT stage (2-year OS: cT3 88.1%, cT4a 79.1%, cT4b 64.7%, p = 0.045). For M0 patients, OS and RFS differed only by pathological (p)T stage. We observed a statistically significant difference in the cumulative incidence of PC by cT stage (2-year CUIN: cT3 3.2%, cT4a 8.5%, cT4b 1.6%, p = 0.01), but not by pT stage. Seventy-nine patients (23%) presented with metastatic disease (M1), eight with PC (2.3%). Overall, eight patients presented with PC (cT4a: n = 4, other stages: n = 4) and 22 developed PC (cT4a: n = 5, other stages: n = 17). PC is uncommon in rectal cancer. MRI-based T stage exhibited an overall association with the cumulative incidence of PC, and descriptively, cT4a stage appears to have the highest CUIN. • In a retrospective study of 343 patients with rectal cancer undergoing baseline MRI and clinical follow-up, we found that peritoneal carcinomatosis was rare. • We observed a significant overall association between PC at presentation and cT stage that appeared to be driven by the higher proportion of cT4a patients presenting with PC. • Among patients that did not present with PC, we observed a significant overall association between time to PC and cT stage that may be driven by the higher cumulative incidence of PC in cT4a patients.

Immune response and locoregional treatments for peritoneal carcinomatosis.

Peritoneal Carcinomatosis (PC) is considered as a terminal disease with short survival. It is treated with palliative therapies, consisting of repeated drainages and sometimes instillation of chemotherapy. Since the nineties, surgery has been combined with more effective systemic chemotherapy, intraperitoneal chemotherapy and hyperthermic intraperitoneal chemotherapy (HIPEC) for the treatment of PC. This combination therapy significantly increases the overall survival of selected PC patients. The understanding of how intraperitoneal chemotherapy and HIPEC can cure patients is still unclear. Experts hypothesized that the efficacy is obtained by the ability of high peritoneal drug exposure and hyperthermia to directly kill cancer cells. Several studies indicate that cancer cells death directly influences the response of the immune system. For this reason, the protective effect of intraperitoneal chemotherapy and HIPEC could be mediated by its ability to kill cancer cells in an immuno-genic way, causing an efficient anticancer immune response. In this review, we investigate the role of the innate peritoneal or locoregional therapy-induced immune response in PC therapy.

Imaging of Gastric Carcinomatosis.

Diagnosing the absence or presence of peritoneal carcinomatosis in patients with gastric cancer, including its extent and distribution, is an essential step in patients’ therapeutic management. Such diagnosis still remains a radiological challenge. In this article, we review the strengths and weaknesses of the different imaging techniques for the diagnosis of peritoneal carcinomatosis of gastric origin as well as the techniques’ imaging features. We also discuss the assessment of response to treatment and present recommendations for the follow-up of patients with complete surgical resection according to the presence of risk factors of recurrence, as well as discussing future directions for imaging improvement.

The Role of Total Parenteral Nutrition in Patients with Peritoneal Carcinomatosis: A Systematic Review and Meta-Analysis.

Simple SummaryPatients with peritoneal carcinomatosis often develop complications which prevent them from receiving adequate oral intake. This can contribute to malnutrition, as well as increased morbidity and mortality. In such patients, total parenteral nutrition, which involves the intravenous administration of nutrients thereby bypassing the oral route, can be lifesaving. In this study, we performed a systematic review and meta-analysis of the existing literature to evaluate the effect of total parenteral nutrition on the survival of patients with peritoneal carcinomatosis. In light of the limited treatment options available, total parenteral nutrition may improve survival outcomes, but further studies are needed to conclude definitively.Peritoneal carcinomatosis (PC) is often associated with malnutrition and an inability to tolerate enteral feeding. Although total parenteral nutrition (TPN) can be lifesaving for patients with no other means of nutritional support, its use in the management of PC patients remains controversial. Therefore, a systematic review and meta-analysis was performed to evaluate the benefit of TPN on the overall survival of PC patients, in accordance with PRISMA guidelines. A total of 187 articles were screened; 10 were included in this review and eight were included in the meta-analysis. The pooled median overall survival of patients who received TPN was significantly higher than patients who did not receive TPN (p = 0.040). When only high-quality studies were included, a significant survival advantage was observed in PC patients receiving TPN (p < 0.001). Subgroup analysis of patients receiving chemotherapy demonstrated a significant survival benefit (p = 0.008) associated with the use of TPN. In conclusion, TPN may improve survival outcomes in PC patients. However, further studies are needed to conclude more definitively on the effect of TPN.

Safety and Effectiveness of High-Precision Hyperthermic Intraperitoneal Perfusion Chemotherapy in Peritoneal Carcinomatosis: A Real-World Study.

BackgroundHyperthermic intraperitoneal chemotherapy (HIPEC) has been reported to effectively control peritoneal carcinomatosis (PC) in various patient populations, but there is a lack of real-world data. This study aimed to examine the safety and effectiveness of HIPEC in patients with PC in a real-world setting.MethodsThis was a retrospective study of patients with PC treated with the high-precision BR-TRG-I type HIPEC device between December 2006 and December 2016. Vital signs during HIPEC and adverse events were recorded. Effectiveness was evaluated by total objective remission rate (ORR), which was based on ascites’ remission 4 weeks after HIPEC.ResultsA total of 1,200 patients were included. There were 518 males and 682 females, with a mean age of 58.6 ± 6.5 years (range, 32–76 years). Among the patients, 93.6% of the patients (1123/1200) successfully received the three sessions of HIPEC, 158 had massive ascites. The changes of vital signs during HIPEC were within acceptable ranges, and patients only had a transient fever and abdominal distension. Regarding the HIPEC-related complications, hemorrhage was observed in seven (0.6%) patients, anastomotic leakage in four (0.5%), and intestinal obstruction in eight (0.7%). Nine (0.8%, 9/1200) patients had CTCAE grade IV bone marrow suppression, and three (0.3%, 3/1200) patients had severe renal failure (SRF), which were considered to be drug-related. The ORR of malignant ascites was 95.6% (151/158).ConclusionThis real-world study strongly suggests that HIPEC was safe in treating PC patients with a low rate of adverse events and leads to benefits in PC patients with massive malignant ascites.

Little Clinical Relevance of Ca125, Cea and Ca125/Cea Ratio for the Differential Diagnosis of Ovarian and Non- Ovarian Carcinomatosis

Background In women, peritoneal cancer is commonly associated to epithelial ovarian cancer. Ovarian peritoneal carcinomatosis patient survival appears to be better in comparison to other peritoneal Malignancies, e.g., colorectal neoplasms or mesotheliomas. Here, we aim to analyze the value of CA125, CEA, CA125/CEA ratio (CCR) tumor markers as preoperative tools for the diagnosis ovarian cancer. Material and methods: From 2005-2008, we recruit prospectively patients admitted to the Navarre Hospital Complex Gynecological service with peritoneal carcinomatosis and suspicion of ovarian cancer origins. The final diagnosis of ovarian cancer carcinomatosis or other malignancies was obtained through Biopsy or cytology. CA 125, CEA and CCR were determined from preoperative venous blood Samples. We compared the tumor markers values between groups of ovarian cancer carcinomatosis and non-ovarian cancer carcinomatosis and calculate the receiver operating curves (ROC) for CA 125, CEA and CCR. Results From 250 patients with suspicion of having ovarian peritoneal carcinomatosis, only 86.4% of the Cases were finally diagnosis of ovarian cancer. Sensitivities of CA125 &gt; 35 mg/dL, CEA &lt; 5 ngr/mL, and CCR &gt; 25 were 95.5%, 91.9%, and 93.6% with specificities of 4.6%, 40.9% and 40.0%, respectively. ROC displayed poor performance for CA125 and CEA for detecting ovarian peritoneal carcinomatosis patients (area under the curve (AUC): 0.69 and 0.63, respectively) while ROC analysis of CCR showed better results (AUC: 0.74). Conclusions: CCR is somehow useful to differentiate between ovarian and non-ovarian peritoneal carcinomatosis patients in comparison with CA125 and CEA alone, although without sufficient specificity for improving the differential diagnosis.

Degree of biliary tract violation during treatment of gallbladder adenocarcinoma is independently associated with development of peritoneal carcinomatosis.

Gallbladder cancer (GBC) is often incidentally diagnosed after cholecystectomy. Intra-operative biliary tract violations (BTV) have been recently associated with development of peritoneal disease (PD). The degree of BTV may be associated with PD risk, but has not been previously investigated. We reviewed patients with initially non-metastatic GBC treated at our institution from 2003 to 2018. Patients were grouped based on degree of BTV during their treatment: major (e.g., cholecystotomy with bile spillage, n = 27, 29%), minor (e.g., intra-operative cholangiogram, n = 18, 19%), and no violations (n = 48, 55%). Overall survival (OS) and peritoneal disease-free survival (PDFS) were evaluated with Kaplan-Meier and Cox proportional hazards modeling. Ninety-three patients were identified; the median age was 64 years (range 31-87 years). Seventy-six (82%) were incidentally diagnosed. The median follow-up was 23 months; 20 (22%) patients developed PD. The 3-year PDFS for patients with major, minor, and no BTV was 52%, 83%, and 98%, respectively (major vs. none: p < 0.001; minor vs. none: p < 0.01). BTV was not associated with 5-year OS (HR 1.53, p = 0.16). Increasing degree of BTV is associated with higher risk of peritoneal carcinomatosis in patients with GBC and should be considered during preoperative risk stratification. Reporting biliary tract violations during cholecystectomy is encouraged.

A Prediction Model for Metachronous Peritoneal Carcinomatosis in Patients with Stage T4 Colon Cancer after Curative Resection.

Simple SummaryMetachronous peritoneal carcinomatosis (mPC) has a significantly worse overall survival than other metastases in colorectal cancer. Exploring the peritoneal cavity is the only effective way to detect early-stage mPC lesions for curative treatment. The operation cannot be justified in all patients but is possible in patients with higher mPC risk. pT1–3 have a significantly lower risk of developing mPC than pT4. Therefore, we focused on analyzing patients with pT4 colon cancer without distant metastasis, developed a prediction model and used data-driven analysis to select patients with a high risk of developing mPC.(1) Background: The aim of this study was to develop a prediction model for assessing individual mPC risk in patients with pT4 colon cancer. Methods: A total of 2003 patients with pT4 colon cancer undergoing R0 resection were categorized into the training or testing set. Based on the training set, 2044 Cox prediction models were developed. Next, models with the maximal C-index and minimal prediction error were selected. The final model was then validated based on the testing set using a time-dependent area under the curve and Brier score, and a scoring system was developed. Patients were stratified into the high- or low-risk group by their risk score, with the cut-off points determined by a classification and regression tree (CART). (2) Results: The five candidate predictors were tumor location, preoperative carcinoembryonic antigen value, histologic type, T stage and nodal stage. Based on the CART, patients were categorized into the low-risk or high-risk groups. The model has high predictive accuracy (prediction error ≤5%) and good discrimination ability (area under the curve >0.7). (3) Conclusions: The prediction model quantifies individual risk and is feasible for selecting patients with pT4 colon cancer who are at high risk of developing mPC.

Circulating tumor DNA as a prognostic factor in peritoneal carcinomatosis after hyperthermic intraperitoneal chemotherapy.

e16280 Background: Hyperthermic intraperitoneal chemotherapy (HIPEC) is the main treatment for peritoneal carcinomatosis (PC).However, It is still a major problem to predict the efficacy of HIPEC. Some studies have shown that peritoneal cancer index (PCI) can be used to predict the efficacy of HIPEC, but the invasiveness and inaccuracy are shortcomings. Therefore, we need a minimally invasive and accurate prediction biomarker. Many studies have confirmed that circulating tumor DNA (ctDNA) can accurately predict the efficacy and prognosis of various solid tumors. This study aimed to evaluate the predictive value of ctDNA from ascites and plasma for HIPEC. Methods: Eligible PC patients should be defintive diagnosed by pathology or cytology. Each patient was treated with HIPEC for 4 times, with an interval of 3 days each time. Plasma and ascites samples were collected before HIPEC and after the last HIPEC. All samples were detected by next generation sequencing (NGS). The molecular tumor burden index (mTBI) and main clone variant allele fraction (VAF) changes were used as the prediction indexes of efficacy. In addition, The changes of common tumor markers such as CEA during the same period were used as controls. Results: A total of 19 patients with PC were enrolled from November 2018 to January 2020. Firstly, the mTBI changes of 14 patients whom had plasma samples at two time points (baseline and postHIPEC)were analyzed. Among them, 3 patients had no gene mutation were detected in two time points. There were significant differences in mTBI before and after HIPEC in the remaining 11 patients (Wilcoxon， p = 0.026). the median Ascites progression free survival (PFS) was 3.35 months (95% CI: 2.34 – 5.13 months), and the median overall survival (OS) was 5.93 months (95% CI: 4.93 – 11.17 months). The mTBI decline was significantly positively correlated with ascites PFS (Spearman r = 0.673, p = 0.023) and moderately positively correlated with OS (Spearman r = 0.510, p = 0.109). The highest VAF in plasma samples was defined as the main clone mutation. The main clone VAF decline was moderately positively correlated with ascites PFS (Spearman r = 0.588, p = 0.057) and slightly positively correlated with OS (Spearman r = 0.386, p = 0.241). As the controls, We found that the common tumor markers decline was no correlated with ascites PFS(Spearman r = 0.091, p = 0.790) and OS (Spearman r = 0.287, p = 0.396). We further analyzed the correlation of VAF between ascites and plasma co-mutation genes in 12 patients. The VAF of co-mutated genes in plasma and ascites was positively correlated (Spearman r = 0.794, p = 0.001). Conclusions: Plasma ctDNA can be used as a biomarker for predicting the efficacy of HIPEC for peritoneal carcinomatosis, and its accuracy is significantly higher than comon tumor markers. However, a larger sample size study are needed to validate our results.