The contemporary management of peritoneal metastasis: A journey from the cold past of treatment futility to a warm present and a bright future.

Peritoneal metastasis (PM) is often regarded as a less frequent pattern of spread; however, collectively across all spectra of primary tumors, the consequences of PM impact a large population of patients annually. Unlike other modes of metastasis, symptoms at presentation or during the treatment course are common, representing an additional challenge in the management of PM. Early efforts with chemotherapy and incomplete surgical interventions transiently improved symptoms, but durable symptom control and survival extension were rare, which established a perspective of treatment futility for PM through most of the 20th century. Notably, the continued development of better systemic therapy combinations, optimization of cytoreductive surgery (CRS), and rigorous investigation of combining regional therapy-specifically hyperthermic intraperitoneal chemotherapy-with CRS, have resulted in more effective multimodal treatment options for patients with PM. In this article, the authors provide a comprehensive review of the data establishing the contemporary approach for tumors with a high frequency of PM, including appendix, colorectal, mesothelioma, and gastric cancers. The authors also explore the emerging role of adding hyperthermic intraperitoneal chemotherapy to the well established paradigm of CRS and systemic therapy for advanced ovarian cancer, as well as the recent clinical trials identifying the efficacy of poly(adenosine diphosphate ribose) polymerase maintenance therapy. Finally, recent data are included that explore the role of precision medicine technology in PM management that, in the future, may help further improve patient selection, identify the best systemic therapy regimens, detect actionable mutations, and identify new targets for drug development.

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.

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.

Enhancing the Efficacy of HIPEC Through Bromelain: A Preclinical Investigation in Appendiceal Cancer.

INTRODUCTION: Appendiceal cancer (AC) excessive mucin production is a barrier to heated intraperitoneal chemotherapy (HIPEC) drug delivery. Bromelain is a pineapple stem extract with mucolytic properties. We explored bromelain treatment effects against mucinous AC in a patient-derived tumor organoid (PTO) model and an AC cell line. PATIENTS AND METHODS: PTOs were fabricated from tumor specimens obtained from patients with AC undergoing cytoreductive surgery with HIPEC. PTOs underwent HIPEC treatment with bromelain, cisplatin, and mitomycin C (MMC) at 37 °C and 42 °C with and without bromelain pretreatment. RESULTS: From October 2020 to May 2023, 16 specimens were collected from 13 patients with low-grade (12/16, 75%) and high-grade AC (4/16, 25%). The mucin-depleting effects of bromelain were most significant in combination with N-acetylcysteine (NAC) compared with bromelain (47% versus 10%, p = 0.0009) or NAC alone (47% versus 12.8%, p = 0.0027). Bromelain demonstrated > 31% organoid viability reduction at 60 min (p < 0.001) and > 66% in 48 h (p < 0.0001). Pretreatment with bromelain increased cytotoxicity of both cisplatin and MMC HIPEC conditions by 31.6% (p = 0.0001) and 35.5% (p = 0.0001), respectively. Ki67, CK20, and MUC2 expression decreased after bromelain treatment; while increased caspase 3/7 activity and decreased Bcl-2 (p = 0.009) and Bcl-xL (p = 0.01) suggest induction of apoptosis pathways. Furthermore, autophagy proteins LC3A/B I (p < 0.03) and II (p < 0.031) were increased; while ATG7 (p < 0.01), ATG 12 (p < 0.04), and Becline 1(p < 0.03), expression decreased in bromelain-treated PTOs. CONCLUSIONS: Bromelain demonstrates cytotoxicity and mucolytic activity against appendiceal cancer organoids. As a pretreatment agent, it potentiates the cytotoxicity of multiple HIPEC regimens, potentially mediated through programmed cell death and autophagy.

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

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

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.

Systematic Cholecystectomy During Cytoreductive Surgery Plus HIPEC: A Critical Analysis of an Empirical Tradition.

BACKGROUND: Some procedures performed during cytoreductive surgery (CRS) and hyperthermic intraoperative intraperitoneal chemotherapy (HIPEC) are based on empirical data. One of these procedures is systematic cholecystectomy. This study aimed to perform a critical analysis of the need for systematic cholecystectomy during CRS+HIPEC of patients with peritoneal carcinomatosis using long-term follow-up data. METHODS: Patients with peritoneal surface malignancies who were candidates for CRS+HIPEC and underwent surgery between January 2008 and December 2022 were analyzed. For patients with gallbladder involvement due to the disease or for patients whose preoperative study showed the presence of cholelithiasis, cholecystectomy was performed as part of the surgery, which was avoided for the remaining patients. All postoperative adverse events that occurred in the first 90 days were recorded, and clinical records focused on the development of biliary pathology during the follow-up period were studied. RESULTS: The results from a consecutive series of 443 patients with peritoneal surface malignancies who underwent surgery between January 2008 and December 2022 were analyzed. The average age of the cohort was 50 years. The median follow-up period for the cohort was 41 months (range, 12-180 months), with a disease-free survival of 17 months. For 373 of the patients, CRS+HIPEC was completed without an associated cholecystectomy, and in 16 of them, the appearance of cholelithiasis was detected during the follow-up period. Only two patients in the series showed complications derived from gallstones and required a delayed cholecystectomy. CONCLUSIONS: Although cholecystectomy is a safe procedure in the context of CRS+HIPEC, it is not risk free, and its routine performance may be unnecessary.

Intra- and Interpatient Drug Response Heterogeneity Exist in Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Nongynecologic Cancers.

BACKGROUND: Select patients with peritoneal metastases are treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). We assayed for intra- and interpatient drug response heterogeneity through testing of patient-derived tumor organoids (PDTOs). METHODS: PDTOs were generated from CRS/HIPEC patients from December 2021 to September 2022 and subjected to an in vitro HIPEC drug screen. Drug response was assessed with a cell viability assay and cleaved caspase-3 staining. RESULTS: A total of 31 patients were consented for tissue collection. Viable tissue was harvested from 23, and PDTO generation was successful in 13 (56%). PDTOs were analyzed from six appendiceal, three colorectal, two small bowel, one gastric, and one adrenal tumor. Drug screen results were generated in as few as 7 days (62%), with an average time of 12 days. Most patients received mitomycin-C (MMC) intraoperatively (n = 9); however, in only three cases was this agent considered the optimal choice in vitro. Three sets of PDTOs were resistant (defined as > 50% PDTO viability) to all agents tested and two were pan-sensitive (defined as 3 or more agents with < 50% PDTO viability). In three patients, organoids were generated from multiple metastatic sites and intrapatient drug response heterogeneity was observed. CONCLUSIONS: Both intra- and interpatient drug response heterogeneity exist in patients undergoing CRS/HIPEC for nongynecologic abdominal cancers. Caution must be used when interpreting patient response to chemotherapeutic agents based on a single site of testing in those with metastatic disease.

Towards Equal Access to Cytoreductive Surgery with Hyperthermic Intraperitoneal Chemotherapy and Survival in Patients with Isolated Colorectal Peritoneal Metastases: A Nationwide Population-Based Study.

BACKGROUND: Before 2016, patients with isolated synchronous colorectal peritoneal metastases (PMCRC) diagnosed in expert centers had a higher odds of undergoing cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) and better overall survival (OS) than those diagnosed in referring centers. Nationwide efforts were initiated to increase awareness and improve referral networks. METHODS: This nationwide study aimed to evaluate whether the between-center differences in odds of undergoing CRS-HIPEC and OS have reduced since these national efforts were initiated. All patients with isolated synchronous PMCRC diagnosed between 2009 and 2021 were identified from the Netherlands Cancer Registry. Associations between hospital of diagnosis and the odds of undergoing CRS-HIPEC, as well as OS, were assessed using multilevel multivariable regression analyses for two periods (2009-2015 and 2016-2021). RESULTS: In total, 3948 patients were included. The percentage of patients undergoing CRS-HIPEC increased from 17.2% in 2009-2015 (25.4% in expert centers, 16.5% in referring centers), to 23.4% in 2016-2021 (30.2% in expert centers, 22.6% in referring centers). In 2009-2015, compared with diagnosis in a referring center, diagnosis in a HIPEC center showed a higher odds of undergoing CRS-HIPEC (odds ratio [OR] 1.64, 95% confidence interval [CI] 1.02-2.67) and better survival (hazard ratio [HR] 0.80, 95% CI 0.66-0.96). In 2016-2021, there were no differences in the odds of undergoing CRS-HIPEC between patients diagnosed in HIPEC centers versus referring centers (OR 1.27, 95% CI 0.76-2.13) and survival (HR 1.00, 95% CI 0.76-1.32). CONCLUSION: Previously observed differences in odds of undergoing CRS-HIPEC were no longer present. Increased awareness and the harmonization of treatment for PMCRC may have contributed to equal access to care and a similar chance of survival at a national level.

Fragmentation of Care in Patients with Peritoneal Metastases Undergoing Cytoreductive Surgery.

BACKGROUND: The delivery of multimodal treatment at a high-volume center is known to optimize the outcomes of gastrointestinal malignancies. However, patients undergoing cytoreductive surgery (CRS) for peritoneal metastases often must 'fragment' their surgical and systemic therapeutic care between different institutions. We hypothesized that this adversely affects outcomes. PATIENTS AND METHODS: Adults undergoing CRS for colorectal or appendiceal adenocarcinoma at our institution between 2016 and 2022 were identified retrospectively and grouped by care network: 'coordinated care' patients received exclusively in-network systemic therapy, while 'fragmented care' patients received some systemic therapy from outside-network providers. Factors associated with fragmented care were also ascertained. Overall survival (OS) from CRS and systemic therapy-related serious adverse events (SAEs) were compared across the groups. RESULTS: Among 85 (80%) patients, 47 (55%) had colorectal primaries and 51 (60%) received fragmented care. Greater travel distance [OR 1.01 (CI 1.00-1.02), p = 0.02] and educational status [OR 1.04 (CI 1.01-1.07), p = 0.01] were associated with receiving fragmented care. OS was comparable between patients who received fragmented and coordinated care in the colorectal [32.5 months versus 40.8 months, HR 0.95 (CI 0.43-2.10), p = 0.89] and appendiceal [31.0 months versus 27.4 months, HR 1.17 (CI 0.37-3.74), p = 0.55] subgroups. The frequency of SAEs (7.8% versus 17.6%, p = 0.19) was also similar. CONCLUSIONS: There were no significant differences in survival or SAEs based on the networks of systemic therapy delivery. This suggests that patients undergoing CRS at a high-volume center may safely receive systemic therapy at outside-network facilities with comparable outcomes.

Cytoreduction and Hyperthermic Intraperitoneal Paclitaxel and Cisplatin for Gastric Cancer with Peritoneal Metastasis.

BACKGROUND: Peritoneal metastasis (PM) is the most common site of dissemination of gastric cancer (GC) and is associated with a poor prognosis. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for GC with PM remains controversial due to modest survival and significant morbidity. METHODS: We conducted a retrospective analysis of patients with GC and PM treated with CRS and HIPEC with cisplatin and paclitaxel for 90 min from June 2019 to December 2022. RESULTS: Twenty-two patients were included and received a median of 7 (interquartile range [IQR] 4-8) cycles of neoadjuvant systemic therapy. Seventeen patients (77%) underwent a single neoadjuvant laparoscopic HIPEC, and six (27%) patients received chemoradiation. The median Peritoneal Carcinomatosis Index at the time of CRS was 1 (IQR 0-4), and 21 patients (95%) underwent complete cytoreduction (CC-0). An R0 resection was achieved in 20 (91%) patients, and the median length of stay was 5.5 (IQR 4-7.5) days. There were six (27%) 90-day major complications (Clavien-Dindo grade ≥ 3), one (4%) Common Terminology Classification for Adverse Events (CTCAE) grade 4 cytopenia, and one (4%) acute kidney injury. The rate of anastomotic leak (all grades) was 14%, the 30-day readmission rate was 18%, and the 90-day mortality rate was 0%. At a median follow-up of 24 months, the median progression-free survival (PFS) and overall survival (OS) were not reached. The 1-, 2-, and 3-year PFS rates were 65%, 56%, and 40%, respectively, and the 1-, 2-, and 3-year OS rates were 96%, 78%, and 55%, respectively. CONCLUSIONS: CRS and HIPEC with paclitaxel and cisplatin is well tolerated and is associated with favorable oncologic and perioperative outcomes.

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

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

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

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

Predictive Value of C-Reactive Protein for Infectious Complications After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy: A Single-Center Prospective Study.

BACKGROUND: Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) can be associated with significant morbidity and prolonged hospital stay. Postoperative infections account for a high burden of these complications. This study aimed to assess the predictive value of postoperative C-reactive protein (CRP) levels for overall infectious complications and anastomotic leaks. METHODS: This was a single-center prospective study of patients undergoing CRS and HIPEC for peritoneal metastases between 2018 and 2020 at Maisonneuve-Rosemont Hospital in Montreal, QC, Canada. CRP levels were measured daily for 10 days following surgery. A comparison was made between patients with infectious complications and those without. RESULTS: Ninety-nine patients were included. Thirty patients had infectious complications (30.3%) and four patients presented an anastomotic leak (4%). CRP levels were significantly higher in patients with infectious complications from postoperative days (PODs) 2-10. Daily cut-off values most accurately predicted infectious complications on day 8 (94.3 mg/L; area under the curve [AUC] 0.85, sensitivity [SE] 76.2%, specificity [SP] 94.7%, positive predictive value [PPV] 88.9%, negative predictive value [NPV] 87.8%; p < 0.0001) and day 9 (72.7 mg/L; AUC 0.89, SE 95.2%, SP 81.8%, PPV 76.9%, NPV 96.4%; p < 0.0001). Patients with infectious complications had longer operative time, higher peritoneal cancer index, and a higher number of intestinal anastomoses, while their baseline characteristics were comparable. CONCLUSION: Measurement of CRP helps predict infectious complications following CRS and HIPEC, particularly on PODs 8 and 9. Cut-off values are more accurate after the first postoperative week, especially in ruling out infectious complications.

Should Cytoreductive Surgery Alone for Peritoneal Metastases of Colorectal Origin be Centralized? A National Study of 4159 Procedures.

BACKGROUND: Addition of oxaliplatin-based hyperthermic intraperitoneal chemotherapy (HIPEC) to cytoreductive surgery (CRS) in the treatment of peritoneal metastases of colorectal origin (CRPM) did not show any survival benefit in the PRODIGE 7 trial (P7). This study aimed to investigate whether perioperative outcomes after CRS alone for CRPM patients is mediated by hospital volume and to determine the effect of P7 on French practice for CRPM patients treated respectively with CRS alone and CRS/HIPEC. METHODS: Data from CRPM patients treated with CRS alone between 2013 and 2020 in France were collected through a national medical database. The study used a cutoff value of the annual CRS-alone caseload affecting the 90-day postoperative mortality (POM) determined from our previous study to define low-volume (LV) HIPEC and high-volume (HV) HIPEC centers. Perioperative outcomes were compared between no-HIPEC, LV-HIPEC, and HV-HIPEC centers. The trend between years and HIPEC rates was analyzed using the Cochrane-Armitage test. RESULTS: Data from 4159 procedures were analyzed. The patients treated in no-HIPEC and LV-HIPEC centers were older compared with HV-HIPEC centers (p < 0.0001) and had a higher Elixhauser comorbidity index (p < 0.0001) and less complex surgery (p < 0.0001). Whereas the major morbidity (MM) rate did not differ between groups (p = 0.79), the 90-day POM was lower in HV-HIPEC centers than in no-HIPEC and LV-HIPEC centers (5.4% vs 15% and 13.3%; p < 0.0001), with lower failure-to-rescue (FTR) (p < 0.0001). After P7, the CRS/HIPEC rate decreased drastically in Cancer centers (p < 0.001), whereas patients treated with CRS alone are still referred to expert centers. CONCLUSIONS: Centralization of CRS alone should improve patient selection as well as FTR and POM. After P7, CRS/HIPEC decreased mostly in Cancer centers, without any impact on the number of CRS-alone cases referred to expert centers.

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

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

Survival Analysis and Recurrence Patterns in 555 Patients with Colorectal Peritoneal Metastases Treated by Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy.

BACKGROUND: The presence at diagnosis, or development of, colorectal peritoneal metastases (CPM) is common in colorectal cancer. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) show promising results in selected patients with CPM. The current study aimed to describe oncologic outcomes of patients with CPM, focusing on recurrence patterns and risk factors for adverse events. METHODS: We conducted a retrospective review of patients with CPM treated by CRS and HIPEC at a single institution between 2000 and 2021. RESULTS: A total of 555 patients were included, of whom 480 (86.5%) had complete cytoreduction, with a median age of 59 years and median Peritoneal Cancer Index (PCI) of 6. Following complete cytoreduction, 5-year overall survival (OS) and disease-free survival (DFS) were 51% and 31%, respectively. In multivariable Cox regression, PCI >6 (hazard ratio [HR] 2.25), pathological node positivity (pN+; HR 1.94), and perineural invasion (HR 1.85) were associated with decreased OS, while PCI >6, pN+, and previous systemic metastases resulted in reduced DFS. Overall, 284 (62%) patients developed recurrence, of whom 97 (34%) had local recurrence (LR), 100 (35%) had systemic recurrence (SR), and 87 (31%) had combined recurrence (5-year OS: 49.3%, 46%, and 37.4%, respectively). Mutated KRAS (mKRAS) was associated with lower 5-year OS (55.8%) and DFS (27.9%) compared with wild-type KRAS (wtKRAS; 70.7% and 37.6%, respectively). In multivariable analyses, mKRAS was related to decreased OS (HR 1.82), DFS (HR 1.55), and SR (OS 1.89), but not to LR. CONCLUSIONS: Complete cytoreduction results in good survival outcomes for patients with CPM. Burden of peritoneal disease and tumor biology are the main predictors of survival. Patients with mKRAS are a high-risk cohort, with increased probability of SR and reduced survival.

Retrospective Evaluation of the Prognostic Value of Histological Growth Pattern in Patients with Colorectal Peritoneal Metastases Undergoing Curative-Intent Cytoreductive Surgery.

BACKGROUND: Two distinct histological growth patterns (HGPs) were described in patients with peritoneal metastasis of colorectal cancer origin (PMCRC) with limited Peritoneal Cancer Index (PCI) ≤ 6 who did not receive neoadjuvant chemotherapy (NAC) and were treated with cytoreductive surgery (CRS) ± hyperthermic intraperitoneal chemotherapy (HIPEC): pushing HGP (P-HGP) and infiltrating HGP (I-HGP). Patients with dominant P-HGP (> 50%) had significantly better disease-free survival (DFS) and overall survival (OS). OBJECTIVE: We aimed to determine whether these previous observations regarding the prognostic value of HGP in patients with PMCRC with low PCI (≤ 6) are also valid in all operable patients, regardless of whether they received NAC or not and regardless of PCI score. METHODS: This was a retrospective study including 76 patients who underwent complete CRS ± HIPEC for PMCRC between July 2012 and March 2019. In each patient, up to five of the largest excised peritoneal nodules were analyzed for their tumor-to-peritoneum interface. Correlations between NAC, HGP, and prognosis were further explored. RESULTS: Thirty-seven patients (49%) had dominant P-HGP and 39 (51%) had dominant I-HGP. On univariate analysis, patients with P-HGP ≤ 50% had significantly lower OS than those with dominant P-HGP > 50% (39 versus 60 months; p = 0.014) confirmed on multivariate analysis (hazard ratio 2.4, 95% confidence interval 1.3-4.5; p = 0.006). There were no significant associations between NAC and type of HGP. CONCLUSIONS: This study confirms the prognostic value and reproducibility of the two previously reported HGPs in PMCRC. Dominant P-HGP is associated with better DFS and OS in patients undergoing curative-intent CRS ± HIPEC compared with I-HGP, independently of the extent of peritoneal disease burden.

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy to Treat Pseudomyxoma Peritonei of Ovarian Origin: A Retrospective French RENAPE Group Study.

BACKGROUND: Ovarian pseudomyxoma peritonei (OPMP) are rare, without well-defined therapeutic guidelines. We aimed to evaluate cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) to treat OPMP. METHODS: Patients from the French National Network for Rare Peritoneal Tumors (RENAPE) database with proven OPMP treated by CRS/HIPEC and with histologically normal appendix and digestive endoscopy were retrospectively included. Clinical and follow-up data were collected. Histopathological and immunohistochemical features were reviewed. RESULTS: Fifteen patients with a median age of 56 years were included. The median Peritoneal Cancer Index was 16. Following CRS, the completeness of cytoreduction (CC) score was CC-0 for 9/15 (60%) patients, CC-1 for 5/15 (33.3%) patients, and CC-2 for 1/15 (6.7%) patients. The median tumor size was 22.5 cm. After pathological review and immunohistochemical studies, tumors were classified as Group 1 (mucinous ovarian epithelial neoplasms) in 3/15 (20%) patients; Group 2 (mucinous neoplasm in ovarian teratoma) in 4/15 (26.7%) patients; Group 3 (mucinous neoplasm probably arising in ovarian teratoma) in 5/15 (33.3%) patients; and Group 4 (non-specific group) in 3/15 (20%) patients. Peritoneal lesions were OPMP pM1a/acellular, pM1b/grade 1 (hypocellular) and pM1b/grade 3 (signet-ring cells) in 13/15 (86.7%), 1/15 (6.7%) and 1/15 (6.7%) patients, respectively. Disease-free survival analysis showed a difference (p = 0.0463) between OPMP with teratoma/likely-teratoma origin (groups 2 and 3; 100% at 1, 5, and 10 years), and other groups (groups 1 and 4; 100%, 66.6%, and 50% at 1, 5, and 10 years, respectively). CONCLUSION: These results suggested that a primary therapeutic strategy using complete CRS/HIPEC for patients with OPMP led to favorable long-term outcomes.

Comparison of outcomes between surgical treatment of colorectal cancer metastatic to the liver and the peritoneum: Review of the literature.

BACKGROUND: Liver and peritoneum are two of the most common sites of colorectal metastases. METHODS: We searched for articles comparing outcomes of surgical management for metastatic colorectal cancer to the liver and peritoneum. CONCLUSION: Cytoreductive surgery/heated intraperitoneal chemotherapy has a similar safety profile and survival outcomes as hepatectomy for colorectal metastases after stratifying by resection status and should be incorporated earlier in the management algorithm for colorectal cancer patients with peritoneal metastases METHODS: We performed a wide search on PubMed, EMBASE, and Google Scholar for articles comparing outcomes of surgical management for metastatic colorectal cancer to the liver and peritoneum. We focused on studies comparing their perioperative clinical outcomes as well as their oncological outcomes. The following words were included in the search: comparison, outcomes, metastasectomy, colorectal cancer, liver, peritoneal surface disease, hepatectomy, and cytoreduction. RESULTS: One hundred and twenty studies were evaluated. Six of these studies met the criteria for this review.