Imaging in malignant peritoneal neoplasms.

Peritoneal malignancies encompass a diverse range of tumors originating within the peritoneum, including primary tumors such as mesothelioma and primary serous peritoneal carcinoma or secondary tumors resulting from the spread of cancers from gastrointestinal, gynecological, and extra-abdominal sources. The traditional approach of palliative care for these malignancies is being replaced by a multimodal strategies that integrates surgery with systemic or intraperitoneal chemotherapy. Notably, cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy has shown significant improvements in survival rates. Imaging is crucial in the multidisciplinary management of these tumors, aiding in diagnosis, staging, restaging, and monitoring therapy response. It is also vital for appropriate patient selection, using the acronym "PAUSE", which involves assessing tumor burden via the peritoneal carcinomatosis index, evaluating patients pre- and post-therapy, detecting complications following therapy, and predicting treatment outcomes. This review explores the imaging manifestations of peritoneal malignancies, distinguishing them from various mimics, and underscores the importance of imaging modalities such as CT, MRI, PET/CT, and PET/MRI in effective decision-making and management.

A rare case of peritoneal tuberculosis mimicking peritoneal carcinomatosis: the ongoing challenge.

Tuberculosis (TB) is a serious infection that can involve any organ system and present in various forms. About one-third of the world's population are carriers of latent TB. Although most cases are from a pulmonary origin, there is a rising prevalence of abdominal TB. Patients with pulmonary or extrapulmonary TB are treated similarly through the use of pharmacological therapy. Nonspecific clinical manifestations of TB have made it difficult for clinicians to diagnose. Peritoneal tuberculosis (PTB) is a serious concern as its symptoms overlap with that of many other chronic conditions, especially in those who are immunocompromised. The lack of highly sensitive and specific testing methods has made early intervention difficult, therefore a high index of suspicion is crucial in the progression of the disease. Here, we present a case of a 71-year-old female with a history of abdominal pain, fever, and weakness. Initial investigation with computed tomography (CT) imaging revealed omental fat stranding that pointed towards peritoneal carcinomatosis (PC) from possible recurrence of her ovarian cancer. Further investigation with a peritoneal biopsy was remarkable for caseating granulomas with fat necrosis confirming extrapulmonary TB. This report highlights a rare case of PTB mimicking PC in an elderly patient who is immunocompromised from the use of long-term corticosteroids who continued to decline after pharmacological treatment of the disease.

Percutaneous Endoscopic Colostomy to Relieve Malignant Bowel Obstruction.

Background: Malignant bowel obstruction due to peritoneal carcinomatosis is a common problem. When surgery is not feasible in the context of a high intraperitoneal tumour burden, other techniques are required. Case report: We report the case of a 67-year-old female with malignant obstruction of the ascending colon. Following an unsuccessful surgical attempt, decompression was successfully achieved via percutaneous endoscopic colostomy using a lumen-apposing metal stent. The patient was able to resume a full oral diet within 2 days. However, local inflammatory complications arose due to faecal contamination of the sutures. Once the sutures were removed, no further interventions were required. Conclusion: Percutaneous endoscopic colostomy is a safe and viable alternative for decompression in malignant bowel obstruction when surgery is not feasible. However, limitations include the risk of local infection due to sutures and its applicability only in cases with distal stenosis. LEARNING POINTS: Malignant bowel obstruction is a frequent challenge in palliative care.Percutaneous colostomy with a lumen-apposing metal stent (LAMS) is a safe and effective option to relieve bowel obstruction.Percutaneous colostomy with a LAMS remains patent in the long term.

The Importance of Preoperative NLR, PLR, and MPV Values in Predicting the Risk of Complications in Colorectal Peritoneal Carcinomatosis.

BACKGROUND: Colorectal cancer peritoneal carcinomatosis (CRC PC) necessitates preoperative assessment of inflammatory markers to predict postoperative outcomes and guide treatment. This study aims to evaluate the prognostic value of preoperative Neutrophil-Lymphocyte Ratio (NLR), Platelet-Lymphocyte Ratio (PLR), and Mean Platelet Volume (MPV) in predicting complications for CRC PC patients undergoing surgery. METHODS: Calculating NLR, PLR, and MPV from patient data: NLR = absolute neutrophil count/total lymphocyte count, PLR = total lymphocyte count/total platelet count × 100, and MPV = platelet crit (PCT)/total platelet count. RESULT: The study included 196 CRC PC patients and found significant relationships between these markers and overall survival (OS). Patients with an NLR of 3.77 had a median OS of 22.1 months, compared to 58.3 months for those with lower NLR (HR 2.7, 95% CI 1.1-5.3, p < 0.001). CONCLUSIONS: For CRC PC patients undergoing CRS+HIPEC, preoperative assessment of NLR, PLR, and MPV can serve as independent prognostic markers for OS. Incorporating these markers into preoperative evaluations may improve patient selection and outcome prediction.

Non-Coding RNAs in Peritoneal Carcinomatosis: From Bench to Bedside.

Peritoneal carcinomatosis represents an advanced stage of tumors within the peritoneal cavity. Once considered an incurable terminal cancer metastasis, contemporary medicine is on the hunt for certain potentially curative options alongside the present day's palliative disease management. However, for most patients, peritoneal carcinomatosis continues to pose a fatal late-stage prognosis with a grim future outlook. Over the past two decades, non-coding RNAs have garnered significant attention due to their undeniable significance in regulating cellular processes across all levels. Disruption of the intricate regulation led by non-coding RNAs has been demonstrated to have a substantial impact on various human diseases, particularly in cancer, including solid tumors originating from the organs of the peritoneal cavity. This review aims to offer a comprehensive overview of the current state of knowledge in the under-researched field of peritoneal carcinomatosis, focusing specifically on the role of non-coding RNAs in the development of this condition and delineating potential avenues for future research.

Management of Peritoneal Surface Malignancies in Saudi Arabia: An Update.

Peritoneal surface malignancies (PSM) are aggressive and associated with poor prognosis. Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) have been used to treat PSM since 1990. In Saudi Arabia, the first HIPEC and pressurized intraperitoneal aerosol chemotherapy (PIPAC) were performed in 2008 and 2019, respectively. With increasing incidences of PSM in Saudi Arabia, the demand for such procedures has grown. This article outlines the status of PSM management in Saudi Arabia and its prospects.

Laparoscopic Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy, an Update From the International PSOGI Registry.

INTRODUCTION: Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are established treatments for peritoneal surface malignancies, traditionally performed via laparotomy. Recent advancements in laparoscopic approaches (L-CRS + HIPEC) have shown promising results in selected patients. METHODS: The PSOGI registry, established in November 2019, collects data from specialized centers performing L-CRS + HIPEC. Data were collected prospectively and analyzed retrospectively, excluding risk-reducing procedures without peritoneal disease. The learning curve was assessed using a 14-cases cutoff. RESULTS: Today, 323 patients have been registered, 193 were included finally. Perioperative outcomes improved after 14 cases: Length of hospital stay was 7.78 ± 3.64 days (consolidation) versus 8.8 ± 8.79 days (learning) and major morbidity was 0% (consolidation) versus 5% (learning), (p = n.s.). Estimated blood loss was lower in the consolidation phase. Oncological outcomes also improved: Recurrence rate was 8.7% (consolidation) versus 17.8% (learning). Disease-free survival 5 years, 65% (learning) versus 88% (consolidation) (p = 0.012). CONCLUSION: The L-CRS + HIPEC is a safe procedure with non-inferior oncologic outcomes which it is evaluating in an IDEAL setting by an international group. The validation of the learning curve, gives us the knowledge that a mentoring program must be setup to reduce the learning curve impact in oncologic failure.

Rare Case of Metachronous Gastric Metastasis from Primary Ovarian Carcinoma.

Metastasis of ovarian cancer to the stomach is extremely rare. The tumors most commonly metastasizing to the stomach include melanoma, breast, lung, and oesophageal carcinoma, while ovarian cancer comprises only 0.013-1.6% of all gastric metastatic tumors. The aim of this study was to present a rare case of an isolated metachronous gastric metastasis from an ovarian carcinoma, in a 59-year-old lady. A 59-year-old lady presented with a right adnexal mass on MRI imaging of the abdomen and pelvis and an elevated serum CA 125 of 4240 IU/ml. She underwent a primary cytoreductive surgery comprising of omentectomy, peritoneal biopsies, pelvic peritonectomy and peritoneal washing cytology, hysterectomy and bilateral salpingo-oophorectomy, and a retroperitoneal and pelvic nodal dissection. The surgical Peritoneal Carcinomatosis Index (PCI) was 5. The final histopathology showed a high-grade serous adenocarcinoma involving the right adnexa. She received six cycles of adjuvant chemotherapy. On a 3-monthly follow-up, the PET scan revealed that a gastric fundic lesion was noted. Investigations revealed a metachronous metastasis from the serous carcinoma of the ovary, confirmed by histopathological evaluation. The patient was treated with surgical resection of the metastasis and systemic chemotherapy to achieve disease control. Gastric metastasis from ovarian cancer should be considered a differential diagnosis in any patient presenting with a gastric mass and a history of ovarian cancer.

How to Implement Pressurized Intraperitoneal Aerosol Chemotherapy into a National Health System Scenario: A Single-Center Retrospective Analysis of Costs and Economic Sustainability at a High-Volume Italian Hospital.

PIPAC is a new surgical procedure and a viable treatment option for PSM patients, due to promising therapeutic outcomes, minimal invasiveness, limited surgical morbidity, and systemic toxicity side effects. However, its implementation throughout hospitals is hard to obtain due to its fragile economical sustainability. A retrospective health economic analysis was conducted in order to evaluate the cost of hospitalization for patients undergoing PIPAC treatment at Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, in Rome. The average cost of a PIPAC procedure was defined based on the cost of surgery (cost of surgical material, operating room, intraperitoneal chemotherapy), hospital stay, diagnostic examinations, and drugs used during the stay. A total of 493 PIPAC procedures were performed on 222 patients with peritoneal metastases or primary peritoneal cancer from 2017 to 2023. Since the mean remuneration for each PIPAC hospitalization is €5916 and the mean expenditure per hospitalization is €6538, this results in an operating profit per PIPAC hospitalization of -€622. The reimbursement of PIPAC treatment by the Italian National Health System currently only partially covers the hospital's costs. Development of specific codes and adequate reimbursement for PIPAC by recognizing this procedure as a proper treatment for peritoneal carcinomatosis is essential.

Is Hyperthermic Intraperitoneal Chemotherapy Appropriate for Colon Cancer?

Colorectal cancer (CRC) with peritoneal metastases is a complex disease and its management presents significant clinical challenges. In well-selected patients at experienced centers, CRS/hyperthermic intraperitoneal chemotherapy (HIPEC) can be performed with acceptable morbidity and is associated with prolonged survival. Based on the results of recent randomized controlled trials, HIPEC using oxaliplatin after CRS with shortened perfusion periods (30 minutes) is no longer recommended. There is a movement toward utilizing mitomycin C as a first-line intraperitoneal agent with extended perfusion times (90-120 minutes); however, there is currently little prospective evidence to support its widespread use.

Flourine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Imaging of Peritoneal Carcinomatosis in Lung Cancer: A Case Study.

Lung cancer with peritoneal carcinomatosis (PC) is a rare disease presentation. The presence of peritoneal disease is a sign of poor prognosis and is hard to diagnose. Flourine-18 fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT) is becoming more clinically significant in the management of patients with PC. A 60-year-old male presented with nonsmall cell lung cancer (NSCLC) and later showed signs of peritoneal disease on 18 F-FDG PET/CT imaging, which subsequently lead to the diagnoses of PC with histopathology from peritoneal biopsy. The patient showed an excellent initial response to their NSCLC treatment but later presented with PC that was shown by FDG-avid ascites and a soft tissue mass in the pelvic area. The abdominal-pelvic lesions were confirmed cytologically to be peritoneal metastatic disease. 18 F-FDG PET/CT demonstrated value in preoperatively directing biopsy for diagnosing PC in this case of NSCLC. Further, 18 F-FDG PET/CT was useful in the monitoring of disease progression and thus influenced management in this case of NSCLC with PC, which is often challenging to detect and manage.

Diagnostic Challenges for Clinicians in Lobular Breast Carcinoma With Peritoneal Carcinomatosis: A Case Report of an Immunocompromised Patient.

Peritoneal carcinomatosis (PC) is a common condition in oncology. The lack of specificity in radiological and clinical characteristics of carcinomatosis makes their etiological diagnosis difficult. Metastatic infiltrating lobular breast cancer with PC is also a common occurrence in daily medical practice. We report the case of a 45-year-old female patient with chronic renal failure undergoing hemodialysis, admitted for lobular breast carcinoma with bone and peritoneal metastases. The surgical exploration including a biopsy revealed peritoneal tuberculosis. The focus of this paper is to discuss the diagnostic traps associated with PC in malignant tumors to highlight the importance of pathological evidence in such cases.

New insights in the management of pseudomyxoma peritonei.

While a rare entity, peritoneal pseudomyxoma treatment evolves. Decision-making criteria improve with imaging development and exploratory laparoscopy. Surgery remains at the core of the therapeutic strategy whatever disease progression. Complete cytoreduction plus hyperthermic intraperitoneal chemotherapy (HIPEC) is standard of care. Iterative cytoreduction or debulking is sometimes justified. Intraperitoneal chemotherapy modalities change with early postoperative HIPEC or pressurized intraperitoneal aerosol chemotherapy. Systemic or local treatment such as new chemo/immuno-therapies or BromAc should improve outcomes. Expertise and multicentric cooperation are more than ever needed.

Long-Term Outcomes following Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Peritoneal Carcinomatosis of Colorectal Origin.

BACKGROUND: Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is a major treatment of colorectal peritoneal carcinomatosis (CPC). The aim was to determine the disease-free survival (DFS) and overall survival (OS) of patients undergoing CRS-HIPEC for CPC and factors associated with long-term survival (LTS). METHODS: consecutive CPC patients who underwent CRS-HIPEC at a HIPEC center between 2007 and 2021 were included. Actual survival was calculated, and Cox proportional hazards models were used to identify factors associated with OS, DFS and LTS. RESULTS: there were 125 patients with CPC who underwent primary CRS-HIPEC, with mean age of 54.5 years. Median follow-up was 31 months. Average intraoperative PCI was 11, and complete cytoreduction (CC-0) was achieved in 96.8%. Median OS was 41.6 months (6-196). The 2-year and 5-year OS were 68% and 24.8%, respectively, and the 2-year DFS was 28.8%. Factors associated with worse OS included pre-HIPEC systemic therapy, synchronous extraperitoneal metastasis, and PCI ≥ 20 (p < 0.05). Progression prior to CRS-HIPEC was associated with worse DFS (p < 0.05). Lower PCI, fewer complications, lower recurrence and longer DFS were associated with LTS (p < 0.05). CONCLUSION: CRS and HIPEC improve OS in CPC patients but they have high disease recurrence. Outcomes depend on preoperative therapy response, extraperitoneal metastasis, and peritoneal disease burden.

Primary Peritoneal Mesothelioma Affecting the Greater Omentum That Mimicked an Omental Infarction: A Case Report.

Introduction: Malignant peritoneal mesothelioma (MPM) is a rare cancer that is associated with asbestos exposure. The diagnosis can be difficult given the nonspecific nature of presenting symptoms and the presence of concomitant confounding findings. Case Presentation: We report a 71-year-old male who presented with right lower quadrant pain and new-onset ascites. CT imaging of the abdomen/pelvis demonstrated omental stranding concerning for a possible omental infarction. Subsequent imaging showed persistent omental edema but no identifiable soft tissue mass. A biopsy of the omentum showed atypical mesothelial proliferation, but pathology was unable to determine if proliferation was a neoplastic versus reactive process. Surgical oncology performed a diagnostic laparoscopy that showed peritoneal studding of the omentum. Subsequent immunohistochemical staining of the omentum demonstrated preservation of BAP1 expression and loss of MTAP expression, consistent with peritoneal mesothelioma. Conclusion: MPM is a rare and aggressive cancer with an overall poor prognosis. The diagnosis of MPM can be difficult based on the nonspecific clinical presentation, insufficient imaging and laboratory testing, and the presence of concomitant confounding findings, such as with this patient and his admitting diagnosis of omental infarction. This case demonstrates the importance of developing a broad differential while maintaining an awareness of heuristics that can influence clinical decision-making.

Efficacy of Hyperthermic Pressurized Intraperitoneal Aerosol Chemotherapy in an In Vitro Model Using a Human Gastric Cancer AGS Cell Line and an Abdominal Cavity Model.

PURPOSE: Peritoneal carcinomatosis (PC) presents a major challenge in the treatment of late-stage, solid tumors, with traditional therapies limited by poor drug penetration. We evaluated a novel hyperthermic pressurized intraperitoneal aerosol chemotherapy (HPIPAC) system using a human abdominal cavity model for its efficacy against AGS gastric cancer cells. MATERIALS AND METHODS: A model simulating the human abdominal cavity and AGS gastric cancer cell line cultured dishes were used to assess the efficacy of the HPIPAC system. Cell viability was measured to evaluate the impact of HPIPAC under 6 different conditions: heat alone, PIPAC with paclitaxel (PTX), PTX alone, normal saline (NS) alone, heat with NS, and HPIPAC with PTX. RESULTS: Results showed a significant reduction in cell viability with HPIPAC combined with PTX, indicating enhanced cytotoxic effects. Immediately after treatment, the average cell viability was 66.6%, which decreased to 49.2% after 48 hours and to a further 19.6% after 120 hours of incubation, demonstrating the sustained efficacy of the treatment. In contrast, control groups exhibited a recovery in cell viability; heat alone showed cell viability increasing from 90.8% to 94.4%, PIPAC with PTX from 82.7% to 89.7%, PTX only from 73.3% to 74.8%, NS only from 90.9% to 98.3%, and heat with NS from 74.4% to 84.7%. CONCLUSIONS: The HPIPAC system with PTX exhibits a promising approach in the treatment of PC in gastric cancer, significantly reducing cell viability. Despite certain limitations, this study highlights the system's potential to enhance treatment outcomes. Future efforts should focus on refining HPIPAC and validating its effectiveness in clinical settings.

Home-Based Trimodal Prehabilitation in Patients with Peritoneal Carcinomatosis Undergoing Cytoreductive Surgery: Effect on Functional Walking Capacity and Skeletal Muscle Mass.

BACKGROUND: Patients with peritoneal carcinomatosis often suffer from loss of skeletal muscle mass and require extensive surgery. Multimodal prehabilitation may improve physical status but its benefits for these specific patients remain unknown. This study aimed to evaluate the effect of prehabilitation on functional walking capacity and skeletal muscle mass, as well as its association with postoperative complications. PATIENTS AND METHODS: A prospective study of patients with peritoneal carcinomatosis following a home-based trimodal prehabilitation program was carried out. Functional walking capacity was assessed with the 6-min walk test (T6MWT), and by the appendicular skeletal muscle index (ASMI) estimated by bioelectrical impedance analysis. Data were collected at the first medical appointment and on the day before surgery. A 90-day postoperative morbidity was registered according to the Clavien-Dindo classification. RESULTS: A total of 62 patients were included in the analysis. Women were more prevalent (77.4%) and peritoneal metastasis from ovarian origin accounted for 48.4%. Clavien II-V grades occurred in 30 (57.7%) patients. After prehabilitation, functional walking capacity improved by 42.2 m (39.62-44.72 m) compared with baseline data (p < 0.001), but no improvement was observed in the ASMI (p = 0.301). Patients able to walk at least 360 m after prehabilitation suffered fewer Clavien-Dindo II-V postoperative complications (p = 0.016). A T6MWT of less than 360 m was identified as an independent risk factor in the multivariable analysis (OR 3.99; 1.01-15.79 p = 0.048). CONCLUSIONS: This home-based trimodal prehabilitation program improved functional walking capacity but not ASMI scores in patients with peritoneal metastasis before surgery. A T6MWT of less than 360 m was found to be a risk factor for postoperative complications.

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.

The Role of Secondary Cytoreduction and Hyperthermic Intraperitoneal Chemotherapy in Recurrent Ovarian Peritoneal Carcinomatosis.

BACKGROUND AND AIMS: Ovarian cancer maintains the highest mortality rate among gynecological malignancies. Unfortunately, two-thirds of cases are diagnosed at an advanced stage with the presence of peritoneal carcinomatosis. In this study, we aimed to present the 7-year results of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in cases where peritoneal carcinomatosis developed during the medical oncological treatment and follow-up after primary high-grade serous ovarian cancer debulking surgeries. PATIENTS AND METHODS: Data from 63 patients collected prospectively in our clinic were retrospectively evaluated. RESULTS: Postoperative Clavien-Dindo grade 3-4 complications occurred in 12 cases (19%) and 14 cases (22.2%), respectively. CD grade 3a complications developed in four cases (6.3%), which were treated with percutaneous drainage catheters, while CD grade 3b complications occurred in eight cases (12.7%), and these cases underwent reoperation. Five cases (7.9%) experienced mortality within the first 30 days. The mean survival time was determined as 44.99 months (36.33-53.65), while the median survival time was 56 months. CONCLUSIONS: In selected patients requiring redo surgery due to recurrent ovarian cancer, secondary cytoreductive surgery and hyperthermic intraperitoneal chemotherapy are associated with longer overall survival and should be considered in the treatment of advanced-stage disease. Further large-scale randomized controlled trials are needed in this regard.

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

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