Treatment for Peritoneal Metastasis of Patients With Colorectal Cancer

Inflammatory and nutritional markers in colorectal cancer: Implications for prognosis and treatment

The prognosis of colorectal cancer (CRC) patients with peritoneal metastasis remains poor despite advancements in detection and treatment. Preoperative inflammatory and nutritional markers have emerged as significant predictors of prognosis in CRC, potentially guiding treatment decisions and improving patient outcomes. This editorial explores the prognostic value of markers such as the neutrophil-to-lymphocyte ratio, hemoglobin, and serum albumin levels. By integrating these markers into prognostic models, clinicians can better stratify patients, personalize treatment strategies, and ultimately enhance clinical outcomes. This review highlights the importance of these markers in providing a comprehensive assessment of patient condition and underscores the need for further research to validate their clinical utility and uncover underlying mechanisms.

Comparison of EPIC Versus HIPEC in the Treatment of Colorectal Peritoneal Metastases and Appendix Tumors Using Inverse Probability of Treatment Weighting

BACKGROUND

The selection of hyperthermic intraperitoneal chemotherapy (HIPEC) or early postoperative intraperitoneal chemotherapy (EPIC) for peritoneal metastases from colorectal cancer or appendiceal neoplasms following cytoreductive surgery (CRS) depends on the surgeon's discretion. This study was designed to compare postoperative and oncologic outcomes of HIPEC and EPIC using inverse probability of treatment weighting (IPTW).

METHODS

This study included 175 patients who received HIPEC or EPIC following CRS at a single tertiary university hospital between December 1999 and December 2020. Inverse probability of treatment weighting analysis was performed to control for pretreatment characteristics between the two groups. Multivariate analysis was performed to determine factors associated with postoperative and survival outcomes.

RESULTS

After IPTW, no significant differences in baseline demographics and tumor characteristics were observed between the two groups. The HIPEC group had a significantly longer operation time than the EPIC group. The EPIC group showed a significantly higher postoperative mortality rate than the HIPEC group. Operation time (odds ratio [OR] 1.01; 95% confidence interval [CI] 1.01-1.02; p < 0.001), bowel anastomosis (OR 7.25; 95% CI 1.16-45.2; p = 0.034), neoadjuvant chemotherapy (OR 7.62; 95% CI 1.85-31.4; p = 0.005), and EPIC (OR 8.76; 95% CI 2.16-35.5; p = 0.002) were independent risk factors for major surgical complications. No association was observed between intraperitoneal chemotherapy type and major hematologic toxicity, overall survival, progression-free survival, or peritoneal progression-free survival.

CONCLUSIONS

EPIC was a risk factor for major surgical complications. Survival outcomes were similar between the two types of intraperitoneal chemotherapy.

Albumin Leakage Level during Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy Is Associated with Major Complications

The clinical consequences of perioperative albumin extravasation accompanying major abdominal surgery remain underexplored. We retrospectively reviewed the data of patients who underwent cytoreductive surgery (CRS) and hyperthermic intraoperative peritoneal chemotherapy (HIPEC). Parameters of albumin kinetics, including serum albumin concentration decrease (∆Alb) and extravasated albumin level (Albshift), were assessed from surgery until postoperative day (POD) 3. Logistic regression analysis identified factors associated with major complications. The association of albumin kinetics with major complications was evaluated using receiver operating characteristic (ROC) curve analysis. Serum albumin levels decreased during surgery and subsequently increased. Of the 121 analyzed patients, 25 (21%) developed major complications. The ∆Alb and Albshift during surgery and on POD 3 were greater in patients who developed major complications than in those who did not (12 ± 12 vs. 6 ± 14, p = 0.032, and 127.5 (71.9) vs. 48.5 (44.9), p < 0.001, respectively). Perioperative ∆Alb and Albshift were associated with major complications. The areas under the ROC curve of Albshift during the 3 days post-surgery and Albshift on POD 3 were 0.843 and 0.910, respectively. Albshift during the 3 days post-surgery and Albshift on POD 3 were correlated with complications (p < 0.05). In conclusion, perioperative albumin loss was associated with major complications in patients undergoing CRS and HIPEC. Albshift was associated with serious complications.

CILP2 is a potential biomarker for the prediction and therapeutic target of peritoneal metastases in colorectal cancer

Peritoneal metastases (PM) in colorectal cancer (CRC) is associated with a dismal prognosis. Identifying and exploiting new biomarkers, signatures, and molecular targets for personalised interventions in the treatment of PM in CRC is imperative. We conducted transcriptomic profiling using RNA-seq data generated from the primary tissues of 19 CRC patients with PM. Using our dataset established in a previous study, we identified 1422 differentially expressed genes compared to non-metastatic CRC. The profiling demonstrated no differential expression in liver and lung metastatic CRC. We selected 12 genes based on stringent criteria and evaluated their expression patterns in a validation cohort of 32 PM patients and 84 without PM using real-time reverse transcription-polymerase chain reaction. We selected cartilage intermediate layer protein 2 (CILP2) because of high mRNA expression in PM patients in our validation cohort and its association with a poor prognosis in The Cancer Genome Atlas. Kaplan-Meier survival analysis in our validation cohort demonstrated that CRC patients with high CILP2 expression had significantly poor survival outcomes. Knockdown of CILP2 significantly reduced the proliferation, colony-forming ability, invasiveness, and migratory capacity and downregulated the expression of molecules related to epithelial-mesenchymal transition in HCT116 cells. In an in vivo peritoneal dissemination mouse knockdown of CILP2 also inhibited CRC growth. Therefore, CILP2 is a promising biomarker for the prediction and treatment of PM in CRC.

Cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy versus R0 resection for resectable colorectal cancer with peritoneal metastases and low peritoneal cancer index scores: a collaborative observational study from Korea and Japan

BACKGROUND

The benefits of hyperthermic intraperitoneal chemotherapy (HIPEC) after cytoreductive surgery (CRS) for colorectal cancer with peritoneal metastasis (CPM) remain controversial. R0 resection without peritoneal stripping might be as effective as CRS plus HIPEC. The authors aimed to compare the long-term oncological outcomes of patients with CPM and peritoneal cancer index (PCI) scores less than or equal to 6 who underwent R0 resection in Japan with those who underwent CRS plus HIPEC in Korea.

MATERIALS AND METHODS

This international, retrospective cohort study was conducted in Korea and Japan using a prospectively collected clinical database. Patients who underwent surgery from July 2014 to December 2021 for CPM with a PCI score of less than or equal to 6 and completeness of the cytoreduction score-0 were included. The primary outcome was relapse-free survival (RFS), and the secondary outcomes were overall survival, peritoneal RFS (PRFS), and postoperative outcomes.

RESULTS

The 3-year RFS was significantly longer in the CRS+HIPEC group than in the R0 resection group: 35.9% versus 6.9% ( P <0.001); 31.0% versus 6.7% ( P =0.040) after propensity score matching. The median PRFS was significantly longer in the CRS+HIPEC group than in the R0 resection group: 24.5 months versus 17.2 months ( P =0.017). The 3-year overall survival and postoperative complications did not significantly differ between the two groups.

CONCLUSIONS

RFS and PRFS rates were significantly prolonged after CRS plus HIPEC, whereas postoperative complications and length of hospital stay were not increased. Therefore, curative CRS plus HIPEC may be considered a treatment strategy for selected patients with resectable CPM and low PCI scores.

Improving nanochemoimmunotherapy efficacy by boosting "eat-me" signaling and downregulating "don't-eat-me" signaling with Ganoderma lucidum polysaccharide-based drug delivery

To address the challenges posed by low immunogenicity and immune checkpoints during cancer treatment, we propose an alternative strategy that combines immunogenic cell death (ICD) effects with CD47/SIRPα blockade to reactivate phagocytosis of tumor cells by macrophages with polysaccharide-based drug delivery. In this study, the EGFR inhibitor gefitinib was identified as a novel CD47 modulator, which promoted the translocation of CD47 molecules from the cell membrane to endosomes through the EGFR-Rab5 pathway, leading to reduced cell surface CD47 levels and limiting interaction with SIRPα. Based on this finding, we developed prophagocytic mixed nanodrugs to enhance macrophage phagocytosis by encapsulating ICD inducer doxorubicin and CD47 inhibitor gefitinib with immunostimulatory polysaccharides from Ganoderma lucidum. This approach downregulated cell surface CD47 expression to attenuate "don't-eat-me" signaling, while increasing doxorubicin accumulation in tumors by inhibiting drug-resistance proteins, leading to more exposure of calreticulin and amplifying the "eat-me" signaling. In vivo experiments demonstrated that this approach significantly suppressed intraperitoneal tumor dissemination, reversed doxorubicin-induced weight loss, and effectively induced macrophage polarization, dendritic cell maturation, and CD8+ T cell activation. These findings highlighted the significant potential of our macrophage-centered therapeutic strategy using polysaccharide-based nanocarriers and provided new perspectives for chemoimmunotherapy.

Recurrence Patterns and Risk Factors after Curative Resection for Colorectal Cancer: Insights for Postoperative Surveillance Strategies

This study aimed to assess recurrence patterns and related risk factors following curative resection of colorectal cancer (CRC). This retrospective observational study was conducted at a tertiary care center, including 2622 patients with stage I-III CRC who underwent curative resection between 2008 and 2018. Hazard rates of recurrence were calculated using a hazard function. The primary outcome was the peak recurrence time after curative resection and secondary outcomes were prognostic factors associated with recurrence. Over a median follow-up period of 53 months, the overall, locoregional and systemic recurrence rates were 8.9%, 0.7%, and 8.5%, respectively. Recurrence rates were significantly higher for rectal cancer (14.9% overall, 4.4% locoregionally, and 12.3% systemically) than for colon cancer (all p < 0.001). The peak recurrence time was 11 months, with variations in hazard rates and curves depending on the tumor location, stage, and risk factors. Patients with AL or CRM involvement exhibited a distinct pattern, with a high hazard rate in the early postoperative period. Understanding these recurrence patterns and risk factors is crucial for establishing effective postoperative surveillance strategies. Our findings suggested that short-interval surveillance should be considered during the first 2 years post-surgery, particularly for high-risk patients who should receive early attention.

Effect of Intraperitoneal Chemotherapy with Regorafenib on IL-6 and TNF-α Levels and Peritoneal Cytology: Experimental Study in Rats with Colorectal Peritoneal Carcinomatosis

Cytoreductive surgery (CRS), combined with hyperthermic intraperitoneal chemotherapy, has significantly improved survival outcomes in patients with peritoneal carcinomatosis from colorectal cancer (CRC). Regorafenib is an oral agent administered in patients with refractory metastatic CRC. Our aim was to investigate the outcomes of intraperitoneal administration of regorafenib for intraperitoneal chemotherapy (IPEC) or/and CRS in a rat model of colorectal peritoneal metastases regarding immunology and peritoneal cytology. A total of 24 rats were included. Twenty-eight days after carcinogenesis induction, rats were randomized into following groups: group A: control group; group B: CRS only; group C: IPEC only; and group D: CRS + IPEC. On day 56 after carcinogenesis, euthanasia and laparotomy were performed. Serum levels of interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α) as well as peritoneal cytology were investigated. Groups B and D had statistically significant lower mean levels of IL-6 and TNF-α compared to groups A and C, but there was no significant difference between them. Both B and D groups presented a statistically significant difference regarding the rate of negative peritoneal cytology, when compared to the control group, but not to group C. In conclusion, regorafenib-based IPEC, combined with CRS, may constitute a promising tool against peritoneal carcinomatosis by altering the tumor microenvironment.

Fluorescence-guided colorectal surgery: applications, clinical results, and protocols

In recent years, the rise of minimally invasive surgery has driven the development of surgical devices. Indocyanine green (ICG) fluorescence imaging is receiving increased attention in colorectal surgery for improved intraoperative visualization and decision-making. ICG, approved by the U.S. Food and Drug Administration in 1959, rapidly binds to plasma proteins and is primarily intravascular. ICG absorption of near-infrared light (750-800 nm) and emission as fluorescence (830 nm) when bound to tissue proteins enhances deep tissue visualization. Applications include assessing anastomotic perfusion, identifying sentinel lymph nodes, and detecting colorectal cancer metastasis. However, standardized protocols and research on clinical outcomes remain limited. This study explores ICG's role, advantages, disadvantages, and potential clinical impact in colorectal surgery.

Do Laparoscopic Approaches Ensure Oncological Safety and Prognosis for Serosa-Exposed Colon Cancer? A Comparative Study against the Open Approach

The adoption of laparoscopic surgery in the management of serosa-exposed colorectal cancer has raised concerns. This study aimed to investigate whether laparoscopic surgery is associated with an increased risk of postoperative recurrence in patients undergoing resection for serosa-exposed colon cancer. A retrospective analysis was conducted on a cohort of 315 patients who underwent curative resection for pathologically confirmed T4a colon cancer without distant metastases at the Asan Medical Center between 2006 and 2015. Patients were categorized according to the surgical approach method: laparoscopic surgery (MIS group) versus open surgery (Open group). Multivariate analysis was employed to identify risk factors associated with overall survival (OS) and disease-free survival (DFS). The MIS group included 148 patients and the Open group had 167 patients. Of the total cohort, 106 patients (33.7%) experienced recurrence during the follow-up period. Rates, patterns, and time to recurrence were not different between groups. The MIS group (55.8%) showed more peritoneal metastasis compared to the Open group (44.4%) among recurrence sites, but it was not significant (p = 0.85). There was no significant difference in the five-year OS (73.5% vs. 78.4% p = 0.374) or DFS (62.0% vs. 64.6%; p = 0.61) between the Open and MIS groups. Age and the pathologic N stage were independently associated with OS, and the pathologic N stage was the only associated risk factor for DFS. The laparoscopic approach for serosa-exposed colon cancer did not compromise the DFS and OS. This study provides evidence that laparoscopic surgery does not compromise oncologic outcomes of patients with T4a colon cancer although peritoneal seeding is the most common type of disease failure of serosa-exposed colon cancer.

Analgesic effects of combined transversus abdominis plane block and intramuscular electrical stimulation in patients undergoing cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy: a randomized controlled trial

BACKGROUND

To evaluate the analgesic efficacy of a four-quadrant transversus abdominis plane (4QTAP) block and a combination of 4QTAP block with needle electrical twitch and intramuscular electrical stimulation (NETOIMS) in patients undergoing cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC).

MATERIALS AND METHODS

Eighty-one patients who underwent CRS followed by HIPEC were included in this study. Patients were randomly assigned to one of three groups: group 1 (intravenous patient-controlled analgesia, control group), group 2 (preoperative 4QTAP block), and group 3 (preoperative 4QTAP block and postoperative NETOIMS). The primary study endpoint was the pain score assessed by the visual analog scale (VAS: 0, no pain; 10, worst imaginable pain) on postoperative day (POD) 1.

RESULTS

The VAS pain score on POD 1 was significantly lower in group 2 than in group 1 (6.0±1.7 and 7.6±1.9, P =0.004), whereas that in group 3 was significantly lower than that in groups 1 and 2 ( P <0.001 and P =0.004, respectively). Opioid consumption and nausea and vomiting incidence during POD 7 were significantly lower in group 3 than in groups 1 and 2. Gait speed and peak cough flow on POD 4 and 7, as well as the quality of recovery (QoR)-40 score on POD 4, were significantly higher in group 3 than in groups 1 and 2.

CONCLUSIONS

The combination of a 4QTAP block with NETOIMS provided more effective analgesia than a 4QTAP block alone after CRS, followed by HIPEC, and enhanced functional restoration and quality of recovery.

Molecular Analyses in Peritoneal Metastasis from Colorectal Cancer: A Review-An English Version

Despite a trend showing continued improvement in survival by combing targeted agents in colorectal cancer, the improvement was limited, and clinically meaningful benefits were not achieved in peritoneal metastasis. The role of cytoreductive surgery (CRS) and proportion of the benefit from hyperthermic intraperitoneal chemotherapy (HIPEC) have been questioned. The PRODIGE 7 study aimed to assess the specific contribution of HIPEC to the survival benefit of peritoneal metastasis from colorectal cancer (CRC-PM) by grouping CRS alone versus CRS with oxaliplatin-based HIPEC, but failed to show any survival improvement. Of these criticisms, oxaliplatin resistance was suggested as the main cause of the negative result. In this regard, the relative resistance to oxaliplatin in consensus molecular subtype 4 colorectal cancer (CRC) is of great interest. Recent treatments for metastatic CRC have gradually moved to precision medicine based on individual biological information through high-throughput technology such as next generation sequencing. This review aimed to provide an overview of the current status of studies reporting the molecular knowledge of CRC-PM.

Recent Advance in the Surgical Treatment of Metastatic Colorectal Cancer-An English Version

Stage IV colorectal cancer (CRC) has heterogeneous characteristics in tumor extent and biology. The overall survival of patients with metastatic CRC has improved with the development of multimodal treatments and new chemotherapeutic drugs. Resection of metastatic CRC is performed for liver, lung, or peritoneal metastases. Conversion surgeries to resect oligometastatic lesions have been developed with tumor regression using chemotherapeutic agents. Two-stage hepatectomy has extended the surgical indications for patients with metastatic CRC. Synchronous liver and primary tumor resection can be considered in patients with adequate conditions. Local ablation with radiotherapy can be used to treat lung metastasis. In the treatment of patients with CRC with peritoneal metastasis, cytoreductive surgery with hyperthermic intraperitoneal chemotherapy can be considered. Surgical treatments should be performed in patients with symptomatic primary tumors with unresectable metastasis. However, primary tumor resection in patients with asymptomatic CRC with synchronous, unresectable metastases did not show overall survival benefits in recent studies. Therefore, the treatment of metastatic CRC is challenging due to the variable tumor extent and heterogenous characteristics. Tailored surgical treatments and multidisciplinary approaches may improve survival and the quality of life in patients with metastatic CRC.

Benign multicystic mesothelioma of appendiceal origin treated by hyperthermic intraperitoneal chemotherapy: A case report

Introduction and importance

Peritoneal benign cystic mesothelioma is a rare benign tumor that originates from a mesothelial proliferative lesion of the peritoneum. However, proper surgical management remains unclear due to its low incidence. We report a clinical case of peritoneal benign cystic mesothelioma treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC).

Case presentation

A 60-year-old female who underwent laparoscopic appendectomy in 2015 presented with abdominal pain in right lower quadrant area. Computed tomography of the abdomen and pelvis revealed a ruptured appendiceal mucocele or mucinous neoplasm, and several seeding-like small nodules in the greater omentum and right peritoneum. Cytoreductive surgery followed by HIPEC was performed; right hemicolectomy and lymph node dissection, omentectomy, and right abdominal partial peritonectomy. HIPEC with mitomycin was conducted for 90 min and an anastomosis between the ileum and colon was made after HIPEC. The pathologic results revealed the colonic mass was a multi-loculated cyst lined by mesothelial cells containing amorphous eosinophilic fibrinoid material, which are common features of benign cystic mesothelioma.

Clinical discussion

Peritoneal benign cystic mesothelioma is known as a borderline disease of mesothelial tumors. Because its etiology is unknown, treatment strategies are not determined.

Conclusion

Cytoreductive surgery followed by HIPEC can be considered to treat peritoneal benign cystic mesothelioma and prevent its malignant transformation.

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Cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy can be considered to treat patients with peritoneal benign cystic mesothelioma.

Surgical treatment for metastatic colorectal cancer

Background: Stage IV colorectal cancer (CRC) exhibits heterogeneous characteristics in tumor extent and biology. The overall survival of patients with metastatic CRC has improved with the development of multimodal treatments and new chemotherapeutic drugs.Current Concepts: Resection of metastatic CRC is performed for liver, lung, or peritoneal metastases. Conversion surgeries to resect oligometastatic lesions have been developed with tumor regression using chemotherapeutic agents. Two-stage hepatectomy has extended the surgical indications for patients with metastatic CRC. Synchronous liver and primary tumor resection can be considered in patients with adequate conditions. Local ablation with radiotherapy can be used to treat lung metastasis. Meanwhile, for treating patients with CRC with peritoneal metastasis, cytoreductive surgery with hyperthermic intraperitoneal chemotherapy can be considered. Surgical treatments should be performed in patients with symptomatic primary tumors with unresectable metastasis. However, in recent studies, primary tumor resection in patients with asymptomatic CRC with synchronous, unresectable metastases did not show overall survival benefits.Discussion and Conclusion: The treatment of metastatic CRC is challenging because of the variable tumor extent and heterogenous characteristics. Tailored surgical treatments and multidisciplinary approaches may improve the survival and quality of life of patients with metastatic CRC.

Direction of diagnosis and treatment improvement in colorectal cancer

Background: Cancer is a major public health problem and the leading cause of death in Korea since 2000. Colorectal cancer is the third leading cause of cancer-related death. Therefore, early detection through screening, surgical techniques improvement, anticancer drugs, adjuvant treatment, and medical resources advancement is important to reduce colorectal cancer-related mortality.Current Concepts: In Korea, the 5-year relative survival rate of patients with colorectal cancer is approximately mid-70%, which is superior to other developed countries, such as the United States, United Kingdom, and Japan, with 60% to 68% because of the well performed screening program and technical improvement. Efforts are underway to conduct active endoscopic treatment for early colorectal cancer and identify cases requiring surgery. Minimally invasive surgery has evolved beyond conventional applications into disease-specific methods, and the robotic system has an important role for evolvement. Performing metastatic colorectal cancer efforts is necessary to improve the survival rate through active surgical treatment and gene therapy.Discussion and Conclusion: Eventually, the role of the patient’s genetic information in diagnosing and treating colorectal cancer is expected to increase. In some cases, diagnosing colorectal cancer using a non-invasive method is already realized. Active surgical treatment based on personal characteristics contributes in improving the treatment outcomes for difficult-to-treat metastatic colorectal cancer. After the period of overall colorectal cancer treatment results improvement, we will undertake the precision treatment era.

Molecular analyses of peritoneal metastasis from colorectal cancer

Background: Despite a trend showing continued improvement in survival by combing targeted agents for colorectal cancer (CRC), the improvement observed is limited. Moreover, clinically relevant benefits were not achieved in peritoneal metastasis cases. The role of cytoreductive surgery (CRS) and the benefits of hyperthermic intraperitoneal chemotherapy (HIPEC) have been questioned. This review aimed to provide an overview of the current status of the studies reporting on the molecular knowledge of peritoneal metastasis from CRC (CRC-PM).Current Concepts: The PRODIGE 7 study was performed to assess the specific contributions of HIPEC to the survival benefit in CRC-PM cases by comparing CRS treatment alone and CRS with oxaliplatin-based HIPEC. However, this study did not reveal any survival improvement, and oxaliplatin resistance was suggested as the main cause of this negative outcome. Hence, the relative resistance to oxaliplatin in consensus molecular subtype (CMS) 4 CRC is of great interest.Discussion and Conclusion: Recent treatments for metastatic CRC have gradually moved to precision medicine based on individual biological information through high-throughput technology, such as next-generation sequencing. In the transcriptome study, CRC-PM was identified as an almost homogeneous CMS4 classification, which is known to have strong resistance to oxaliplatin-based chemotherapy. These results suggest the need to clarify complex sub-signal transmission pathways derived from transcriptome or proteome studies of CRC-PM. Finally, to compare two studies, it is necessary to establish a representative patient group and consider standardized sample collection, treatment, and analysis.

Patients with Metachronous Peritoneal Metastatic Mucinous Colorectal Adenocarcinoma Benefit More from Cytoreductive Surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) than Their Synchronous Counterparts

Background: Mucinous adenocarcinoma is a frequent subtype in colorectal cancer (CRC). A higher initial T-stage, poorer differentiation, worse response to anti-tumor therapies, and shorter survival are characteristic of mucinous CRC. Moreover, the therapeutic benefit of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS + HIPEC) in mucinous CRC has not been significantly investigated. Methods: A retrospective analysis of 218 CRC patients with synchronous or metachronous peritoneal metastases was conducted. Results: 129 and 89 patients had synchronous and metachronous metastases, and 36 (27.8%) and 22 (24.8%) of these were mucinous CRC, respectively. Mucinous CRC was more frequent in the proximal colon, with a higher T-stage and N-stage and with an average peritoneal carcinomatosis index that was 2 values higher. Disease-specific survival was significantly worse in the synchronous mucinous group (median survival: 22.4 months vs. 36.3 months, p = 0.0229). In contrast, no such difference was observed in the metachronous cohort (32.6 months vs. 34.4 months, p = 0.6490). Conclusions: In the case of synchronous peritoneal metastases originating from mucinous CRC, the positive effect of CRS+HIPEC cannot be verified, and the added value of this highly invasive treatment is therefore somewhat questioned. However, CRS + HIPEC is recommended for metachronous metastases, since no difference between the two CRC-subtypes could be verified.

The Onset of In-Vivo Dehydration in Gas -Based Intraperitoneal Hyperthermia and Its Cytotoxic Effects on Colon Cancer Cells

Background

Peritoneal metastasis (PM) is an ongoing challenge in surgical oncology. Current therapeutic options, including intravenous and intraperitoneal (i.p.) chemotherapies display limited clinical efficacy, resulting in an overall poor prognosis in affected patients. Combined hyperthermia and dehydration induced by a high-flow, gas-based i.p. hyperthermic procedure could be a novel approach in PM treatment. Our study is the first to evaluate the therapeutic potential of i.p. dehydration, hyperthermia, as well as the combination of both mechanisms in an in-vivo setting.

Methods

For this study, three swine were subjected to diagnostic laparoscopy under a high-flow air stream at 48°, 49° and 50°Celsius (C). Hygrometry of the in- and outflow airstream was measured to calculate surface evaporation and i.p. dehydration. To analyze the effects of this concept, in vitro colon cancer cells (HT-29) were treated with hyperthermia and dehydration. Cytotoxicity and cell viability were measured at different time intervals. Additionally, structural changes of dehydrated cells were analyzed using scanning electron microscopy.

Results

According to our results, both dehydration and hyperthermia were cytotoxic to HT-29 cells. However, while dehydration reduced cell viability, hyperthermia did not. However, dehydration effects on cell viability were significantly increased when combined with hyperthermia (p<0.01).

Conclusions

Changes to the physiological milieu of the peritoneal cavity could significantly reduce PM. Therefore, limited dehydration of the abdominal cavity might be a feasible, additional tool in PM treatment. Further studies are required to investigate dehydration effects and their applicability in PM management.