Peritoneal Metastases in Colorectal Cancer: Biology and Barriers

Genetic specificity study using next-generation sequencing (NGS) of peritoneal metastatic colorectal cancer compared to primary colorectal cancer

BACKGROUND

In patients with colorectal cancer, peritoneal metastases are the second most frequent metastatic lesion after liver metastases. Peritoneal metastases have a very poor prognosis, with a median survival time of 5-7 months. Currently, there is a lack of research on the genetic differences between primary colorectal cancer and peritoneal metastases. Therefore, we aimed to identify their genetic characteristics through a cancer panel test using next-generation sequencing.

OBJECTIVE

We aim to investigate the specificity of genetic variants in primary colorectal cancer and peritoneal metastases.

METHODS

We recruited patients with stage I, II, and III primary colorectal cancer and peritoneal metastases for genetic analysis using NGS. Samples were collected from patients who underwent surgery at Dankook University Hospital and consented to genetic testing. NGS was performed using a cancer panel.

RESULTS

Among 36 patients with primary cancer, TP53 gene mutation was identified the most in 25 patients (69%), followed by APC gene mutation in 19 patients (53%), and KRAS gene mutation in 17 patients (47%). In the peritoneal metastasis patient group, unlike the primary cancer patient group, KRAS gene mutations were the most common 6 patients (55%), followed by TP53 gene mutations in 4 patients (36%) and PIK3CA gene mutations in 2 patients (18%).

CONCLUSION

The small number of surgical cases of peritoneal metastases was a limitation of our sample size. Nevertheless, we identified differences in the alterations of specific genes between primary and peritoneal metastases. Acquiring additional cases and collecting more data will provide deeper insights into these cancers.

Microvascularized tumor assembloids model for drug delivery evaluation in colorectal cancer-derived peritoneal metastasis

Peritoneal metastasis (PM) is a fatal state of colorectal cancer, and only a few patients may benefit from systemic chemotherapy. Although hyperthermic intraperitoneal chemotherapy (HIPEC) brings hope for affected patients, the drug development and preclinical evaluation of HIPEC are seriously lagging behind, mainly due to the lack of an ideal in vitro PM model that makes drug development over-reliant on expensive and inefficient animal experiments. This study developed an in vitro colorectal cancer PM model [microvascularized tumor assembloids (vTA)] based on an assembly strategy of endothelialized microvessels and tumor spheroids. Our data showed that the in vitro perfusion cultured vTA could maintain a similar gene expression pattern to their parental xenografts. Also, the drug penetration pattern of the in vitro HIPEC in vTA could mimic the drug delivery behavior in tumor nodules during in vivo HIPEC. More importantly, we further confirmed the feasibility of constructing a tumor burden-controlled PM animal model using vTA. In conclusion, we propose a simple and effective strategy to construct physiologically simulated PM models in vitro, thus providing a basis for PM-related drug development and preclinical evaluation of locoregional therapies. STATEMENT OF SIGNIFICANCE: This study developed an in vitro colorectal cancer peritoneal metastasis (PM) model based on microvascularized tumor assembloids (vTA) for drug evaluation. With perfusion culture, vTA could maintain a similar gene expression pattern and tumor heterogeneity to their parental xenografts. And the drug penetration pattern in vTA was similar to the drug delivery behavior in tumor nodules under in vivo treatment. Moreover, vTA was more conducive to construct PM animal models with controllable tumor burden. In conclusion, the construction of vTA could provide a new strategy for the PM-related drug development and preclinical evaluation of locoregional therapies.

Predictive Genetic Biomarkers for the Development of Peritoneal Metastases in Colorectal Cancer

Metastatic colorectal cancer (CRC) is a common cause of cancer-related mortality, of which peritoneal metastases (PMs) have the worse outcome. Metastasis-specific markers may help predict the spread of tumor cells and select patients for preventive strategies. This exploratory pilot study aimed to gain more insight into genetic alterations in primary CRC tumors, which might be a predictive factor for the development of PM. Forty patients with T3 stage CRC were retrospectively divided in three groups: without metachronous metastases during 5-year follow-up (M0, n = 20), with metachronous liver metastases (LM, n = 10) and with metachronous PM (PM, n = 10). Patients with synchronous metastases were excluded. Primary formalin-fixed paraffin-embedded tumor samples were analyzed via comprehensive genome sequencing (TSO500 analysis) to identify DNA alterations and RNA fusion transcripts in 523 genes and 55 genes, respectively. Thirty-eight samples were included for final analysis. Four M0 tumors and one PM tumor were microsatellite instable. BRAF mutations were uniquely identified in three microsatellite-stable (MSS) PM tumors (37.5%, p = 0.010). RNA analysis showed an additional FAM198A-RAF1 fusion in one PM sample. BRAF p.V600E mutations were only present in PM patients with MSS tumors. Greater attention should be paid to BRAF-mutated tumors in relation to the development of metachronous PM.

Cytoreductive surgery and intraperitoneal chemotherapy for peritoneal metastasis of colorectal cancer: long-term follow-up results at a single institution in Korea

PURPOSE

This study aimed to examine the 7-year follow-up results of cytoreductive surgery (CRS) and intraperitoneal chemotherapy (IPC) for peritoneal metastasis (PM) of colorectal cancer.

METHODS

We performed 54 cases of CRS and IPC in 53 patients with PM of colorectal cancer from December 2011 to December 2013. We prospectively collected data and analyzed peritoneal carcinomatosis grade, completeness of cytoreduction, and long-term follow-up (median, 10 [range, 2-92] months) results.

RESULTS

The mean peritoneal cancer index was 15 (1 ~ 35), and complete cytoreduction was possible in 35 (64.8%) patients. Excluding the four patients who died, 11 (22.4%) out of the 49 patients were alive at the time of the last follow-up, and the overall median survival period was 10.3 months. The overall 2- and 5-year survival rates were 31% and 17%, respectively. Patients with complete cytoreduction had a median survival period of 22.6 months, which was significantly longer than that for patients without complete cytoreduction (3.5 months) (P < 0.001). The 5-year survival rate for patients with complete cytoreduction was 24%, and four patients were still alive without disease.

CONCLUSIONS

CRS and IPC show a 5-year survival rate of 17% in patients with PM of colorectal cancer. A possibility of long-term survival is observed in a selected group. Multidisciplinary team evaluation for careful patient selection and CRS training program to achieve complete cytoreduction are significantly important factors in improving survival rate.

PI3K Pathway Alterations in Peritoneal Metastases are Associated with Earlier Recurrence in Patients with Colorectal Cancer Undergoing Optimal Cytoreductive Surgery

BACKGROUND

Colorectal cancer with peritoneal metastasis (CRC-PM) represents a biologically heterogeneous disease; yet little is known regarding the impact of tumor biology on survival outcomes following optimal cytoreductive surgery (CRS). We analyzed the frequency of alterations in cancer signaling pathways in patients with CRC-PM and their impact on recurrence-free survival (RFS) following optimal CRS.

METHODS

Thirty-five consecutive CRC-PM patients who underwent optimal CRS/HIPEC and next generation sequencing of peritoneal metastases were included in the study. Alterations in eight cancer-related signaling pathways were analyzed: Wnt/APC, p53, RTK-RAS, PI3K, TGF-B, Notch, Myc, and cell cycle. The association of pathway alterations with RFS and OS following optimal cytoreduction was estimated using Cox proportional hazard modeling.

RESULTS

The most frequently altered pathways were Wnt/APC (63%), p53 (63%), RTK-RAS (60%), and PI3K (23%). Among optimally cytoreduced patients with CRC-PM, PI3K pathway alterations were an independent predictor of worse RFS (hazard ratio 3.2, 95% confidence interval CI 1.3-8.3, p = 0.01) with a clinically meaningful impact on median months to recurrence (5 vs. 13 months, p = 0.02). Alterations in p53, Wnt, and RTK-RAS pathways were not significantly associated with a difference in RFS following CRS. Alterations in the four pathways were not associated with differences in OS following CRS (median OS was 50 (interquartile range 23-80) months).

CONCLUSIONS

In patients with CRC-PM, PI3K pathway alterations are associated with earlier recurrence following optimal CRS, which may represent a distinct molecular subtype. This novel finding can tailor clinical trials by using PIK3CA-directed interventions to reduce risk of recurrence after optimal CRS.

Insurance Authorization Barriers in Patients Undergoing Cytoreductive Surgery and HIPEC

BACKGROUND

Indications for cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) exist across multiple histologies, but little data exist on the impact of insurance authorization on access to these therapies. Given the evolving role of CRS/HIPEC, we sought to characterize insurance approval and delays in patients undergoing these therapies.

PATIENTS AND METHODS

A retrospective review was performed at a high-volume tertiary center of patients who received CRS/HIPEC from 2017 to 2021. Collected data included patient demographics, tumor histologic characteristics, insurance type, approval/denial history, and time to prior authorization approval. Descriptive statistics were performed.

RESULTS

In total, 367 patients received CRS/HIPEC during the study period. They had a median age of 59 (IQR 49-67) years, 35% were male, and 76% were white. Of the patients requiring prior authorization, 14 of 104 (13%) patients were denied prior authorization and required appeal. Median time between authorization request and approval was 33 (IQR 28-36) days. These cases generated 410 insurance authorization requests, 94 (23%) of which were not initially approved and required appeal. The rate of upfront denial was 21.1% in patients with public insurance compared with 23.4% in patients with private insurance. Gastric cancer was the most common histology among denied cases (55%), followed by colorectal, appendiceal, and gynecologic malignancies.

CONCLUSIONS

Despite the broadening indications for and data supporting CRS/HIPEC, a significant proportion of patients still face hurdles in attaining insurance approval and coverage for these therapies. Addressing barriers to insurance approval is imperative to decrease therapeutic delay and improve access to data-driven care.

Long-term outcomes of elderly patients with peritoneal metastases of colorectal origin after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

INTRODUCTION

Cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) were reportedly safe for the elderly. However, long-term survival data in this subgroup of patients are scarce. Our aim was to evaluate the peri-operative and long-term outcomes of CRS + HIPEC in colorectal peritoneal metastases (CRC-PM) in patients ≥70 years of age.

MATERIAL AND METHODS

We retrospectively analyzed our combined institutional databases for patients who underwent CRS + HIPEC for CRC-PM. Clinical and pathological characteristics, as well as overall survival (OS) and progression-free survival (PFS) were compared between the groups. Tumor extent was measured by the peritoneal carcinomatosis index (PCI) and completeness of cytoreduction by the CCR score. Major morbidity was defined according to Clavien-Dindo classification.

RESULTS

The dataset of 159 patients included 33 elderly and 126 non-elderly patients. Clinical characteristics between the groups differed only in medical comorbidities (Charlson comorbidity index 10 vs. 7, P < 0.001) and delivery of post-HIPEC adjuvant treatment (12.5% vs. 43.8%, P = 0.004). Overall PCI and CCR0 rates were similar between the groups, as were length of stay and major morbidity and mortality rates. Long-term outcomes in the elderly group were lower than those of the non-elderly (median OS: 21.8 vs. 40.5 months, P < 0.001; median PFS: 6 vs. 8 months, P = 0.02, respectively).

CONCLUSIONS

CRS + HIPEC in selected elderly patients can be safe in terms of postoperative morbidity and mortality. However, despite the same surgical extents and radicality, their long-term outcomes are inferior, possibly due to under-usage of systemic chemotherapy.

Prognostic Factors of Survival in Patients with Peritoneal Metastasis from Colorectal Cancer

Objectives: The aim of this study was to analyze the prognostic factors of survival in patients with peritoneal metastasis (PM) from colorectal cancer (CRC). The type of relationship between survival and the PM time of detection was used to determine whether it was synchronous with the primary tumor or metachronous. Patients and Methods: Retrospective observational study. It included patients treated for colorectal adenocarcinoma diagnosed between January 2005 and December 2019 who presented PM at the time of diagnosis or during follow-up. Variables, such as sex, age, differentiation grade, positive adenopathy (pN+), tumor size (pT), tumor location, mucinous component, peritoneal carcinomatosis index (PCI), and KRAS mutational status, were analyzed. Results: During the study period, 1882 patients were surgically treated for CRC in our hospital. Of these, 240 patients (12.8%) were included in the study after evidence of PM. The mean age was 67 ± 12 years (range: 32−92 years), and 114 patients were female (47.5%). The mean follow-up was 20 ± 13 months (median 12 months). The Kaplan−Meier survival at 36 months was higher in patients with metachronous PM (24% vs. 8%; p = 0.002), WT-KRAS tumors (31% vs. 15%; p < 0.001), N0 stage (30% vs. 19%; p < 0.001), T3 stage tumors (18% vs. 19% in T4A and 3% in T4B; p > 0.001), and tumors with classic adenocarcinoma histology (18% vs. 8%; p = 0.011). Patients with a PCI of 1−10 showed a likelihood of survival at 36 months of 56%, which was longer than that found in patients with a PCI of 11−20 (8%) or a PCI of >20 (0%) (p < 0.001). In the multiple regression analysis, the factors with an independent prognostic value were: poor grade of differentiation (HR 1.995; 95% CI: 1.294−3.077), KRAS mutation (HR 1.751; 95% CI: 1.188−2.581), PCI 11−20 (HR: 9.935; 95% CI: 5.204−18.966) and PCI > 20 (HR: 4.011; 95% CI: 2.291−7.023). Conclusions: PCI should continue as the as the most useful prognostic indicator in order to assess prognostic estimations as well as therapeutic and surgical decisions, but tumor grade and KRAS mutational status may help in the treatment decision process by providing complementary information. The time of PM detection did not achieve statistical significance in the multiple regression analysis.

Investigating the mechanisms of peritoneal metastasis in gastric adenocarcinoma using a novel ex vivo peritoneal explant model

Gastric adenocarcinoma, commonly known as stomach cancer, has a predilection for metastasis to the peritoneum, which portends limited survival. The peritoneal metastatic cascade remains poorly understood, and existing models fail to recapitulate key elements of the interaction between cancer cells and the peritoneal layer. To explore the underlying cellular and molecular mechanisms of peritoneal metastasis, we developed an ex vivo human peritoneal explant model. Fresh peritoneal tissue samples were suspended, mesothelial layer down but without direct contact, above a monolayer of red-fluorescent dye stained AGS human gastric adenocarcinoma cells for 24 h, then washed thoroughly. Implantation of AGS cells within the explanted peritoneum and invasion beyond the mesothelial layer were examined serially using real-time confocal fluorescence microscopy. Histoarchitecture of the explanted peritoneum was preserved over 5 days ex vivo. Both implantation and invasion were suppressed by restoration of functional E-cadherin through stable transfection of AGS cells, demonstrating sensitivity of the model to molecular manipulation. Thus, our ex vivo human peritoneal explant model permits meaningful investigation of the pathways and mechanism that contribute to peritoneal metastasis. The model will facilitate screening of new therapies that target peritoneal dissemination of gastric, ovarian and colorectal cancer.

A Nomogram for Predicting Survival in Patients With Colorectal Cancer Incorporating Cardiovascular Comorbidities

Background

Cardiovascular comorbidities (CVCs) affect the overall survival (OS) of patients with colorectal cancer (CRC). However, a prognostic evaluation system for these patients is currently lacking.

Objectives

This study aimed to develop and validate a nomogram, which takes CVCs into account, for predicting the survival of patients with CRC.

Methods

In total, 21,432 patients with CRC were recruited from four centers in China between January 2011 and December 2017. The nomogram was constructed, based on Cox regression, using a training cohort (19,102 patients), and validated using a validation cohort (2,330 patients). The discrimination and calibration of the model were assessed by the concordance index and calibration curve. The clinical utility of the model was measured by decision curve analysis (DCA). Based on the nomogram, we divided patients into three groups: low, middle, and high risk.

Results

Independent risk factors selected into our nomogram for OS included age, metastasis, malignant ascites, heart failure, and venous thromboembolism, whereas dyslipidemia was found to be a protective factor. The c-index of our nomogram was 0.714 (95% CI: 0.708–0.720) in the training cohort and 0.742 (95% CI: 0.725–0.759) in the validation cohort. The calibration curve and DCA showed the reliability of the model. The cutoff values of the three groups were 68.19 and 145.44, which were also significant in the validation cohort (p < 0.001).

Conclusion

Taking CVCs into account, an easy-to-use nomogram was provided to estimate OS for patients with CRC, improving the prognostic evaluation ability.

The Role of Hyperthermic Intraperitoneal Chemotherapy for Non-colorectal Peritoneal Surface Malignancies

BACKGROUND

Peritoneal carcinomatosis, from a variety of gastrointestinal and gynecological malignancies, has been historically challenging to treat and there remains a wide range of biologic aggressiveness in these patients. Malignancies commonly associated with PC include those of colorectal, appendiceal, gastric, ovarian, sarcoma, small intestinal, and primary peritoneal origin among others. Advances in our understanding of this unique disease process have led to significant interest in cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) as an emerging treatment option. The goal of CRS-HIPEC is to remove all visible macroscopic disease while preserving organ function, and then treat microscopic disease through perfusion of the peritoneal cavity with heated chemotherapy.

PURPOSE

Although recent reviews have focused on the management of peritoneal carcinomatosis secondary to colorectal cancer given the publication of several recent randomized controlled trials, the purpose of the current review is to summarize the evidence on CRS-HIPEC for non-colorectal peritoneal surface malignancies, including appendiceal neoplasms, malignant peritoneal mesothelioma, gastric cancer, and ovarian cancer.

RESULTS

While retrospective studies have clarified the importance of prognostic factors such as the peritoneal carcinomatosis index, completeness of cytoreduction, histopathological characteristics, and lymph node positivity, the lack of convincing level 1 evidence for the use of CRS-HIPEC has led to it remaining a highly controversial topic.

CONCLUSION

The decision to utilize CRS-HIPEC should involve a multidisciplinary team approach and evaluation of prognostic factors to balance the short-term morbidity of the operation with maximum long-term benefits. Large, multi-institutional groups and ongoing trials hold promise for clarifying the role of CRS-HIPEC in peritoneal surface malignancies.

Metastatic Colorectal Cancers with Mismatch Repair Deficiency Result in Worse Survival Regardless of Peritoneal Metastases

BACKGROUND

Mismatch-repair deficiency (dMMR) predicts worse chemoresponsiveness but better survival in early-stage colorectal adenocarcinoma. This study examined metastatic colorectal and appendix cancers with and without peritoneal metastasis (PM) in the National Cancer Database (NCDB), hypothesizing that dMMR tumors show better survival.

METHODS

Stage 4 colon, rectum, and appendix cancers (2010-2016) were identified in the NCDB (including goblet cell carcinoids, excluding neuroendocrine tumors). Stage 4 disease without liver, bone, brain, lung, or distant nodal metastases defined PM. Fisher's exact tests were used to compare proportions, and Kaplan-Meier analysis was used to evaluate survival.

RESULTS

Of 130,125 stage 4 colon, rectum, and appendix cancers, 27,848 (21.4%) had PM. Appendix primary tumors had PM more commonly than colon or rectum cancer (83.6% vs. 20.6% and 12.1% of stage 4 cases; p < 0.0001). More PM patients had MMR testing than patients with other metastasis (OM) (21.4% vs. 16.1%), and testing increased from 9.6% in 2010 to 26.3% in 2016 (both p < 0.0001). Among the PM patients, MMR testing was least common for appendix cancers (9.0%). When tested, PM patients more often had dMMR (22.9% [1122/4900] vs. 15.4% [2532/16,495] of OM patients; p < 0.0001). Colon primary tumor had dMMR most frequently (25.0% vs. 14.6% and 14.5% for rectal and appendix tumor; p < 0.0001). Most PM patients received chemotherapy (66.2%). Immunotherapy use increased over time (1.1% of PM diagnoses in 2010 vs. 20.8% in 2016). For MMR-tested stage 4 patients, dMMR correlated with worse survival (median OM, 19.7 vs. 23.9 months, p < 0.0001; median PM, 19.9 vs. 24.6 months, p = 0.035).

CONCLUSIONS

The NCDB showed dMMR predicting worse survival for stage 4 colorectal cancers with and without PM and dMMR existing in 14.5-25% of tested patients, suggesting that increased attention to MMR testing in stage 4 colorectal and appendix cancers can identify many patients who could potentially benefit from immunotherapy.

Biodegradable Implants Combined with Immunogenic Chemotherapy and Immune Checkpoint Therapy for Peritoneal Metastatic Carcinoma Postoperative Treatment

Peritoneal seeding represents one of the most frequent sites of metastasis for late-stage gastrointestinal and gynecological cancer. At present, the major treatment method for peritoneal metastatic carcinoma (PMC) is the combination of cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). Nevertheless, the 5 year survival rate of patients after these treatments is still far from satisfactory. Here, we report a biodegradable implant co-loaded with doxorubicin (DOX) and anti-PD-1 monoclonal antibody (aPD-1) (BI@DOX+aPD-1) for a combination of immunogenic chemotherapy and immune checkpoint therapy for PMC postoperative treatment. The bio-implant is fabricated with oxidized dextran (ODEX) and 4-arm poly(ethylene glycol) amine (4-arm PEG-NH₂) by Schiff's base reaction at mild conditions, with DOX and aPD-1 loaded inside during and after the fabrication process, respectively. In vitro studies confirmed the slow and sustained release of DOX and aPD-1 from the bio-implants. In vivo studies showed that the bio-implants could be gradually degraded and maintain relatively high concentrations of therapeutic agents in the mouse abdomen. In a murine CT26 PMC model, the BI@DOX+aPD-1 resulted in a 89.7% tumor-suppression rate after peritoneal implantation. Importantly, the combination therapy of DOX and aPD-1 in the bio-implant showed an excellent synergistic effect with a Q value of 2.35. This easy-fabricated bio-implant combined with DOX and aPD-1 should be promising for clinical PMC postoperative treatment.