Review: Pathology and Its Clinical Relevance of Mucinous Appendiceal Neoplasms and Pseudomyxoma Peritonei

First-line palliative systemic therapy alternated with oxaliplatin-based pressurized intraperitoneal aerosol chemotherapy for unresectable colorectal peritoneal metastases: A single-arm phase II trial (CRC-PIPAC-II)

BACKGROUND

Palliative systemic therapy alternated with electrostatic precipitation oxaliplatin-based pressurized intraperitoneal aerosol chemotherapy (ePIPAC) has never been prospectively investigated in patients with unresectable colorectal peritoneal metastases (CPM). The CRC-PIPAC-II study aimed to assess safety, feasibility and efficacy of such bidirectional therapy.

METHODS

This two-center, single-arm, phase II trial enrolled chemotherapy-naïve patients to undergo three treatment cycles, consisting of systemic therapy (CAPOX, FOLFOX, FOLFIRI, or FOLFOXIRI, all with bevacizumab) and oxaliplatin-based ePIPAC (92 mg/m2) with intravenous leucovorin (20 mg/m2) and 5-fluorouracil (400 mg/m2). Primary outcome were major treatment-related adverse events. Secondary outcomes included minor events, tumor response, progression-free survival (PFS) and overall survival (OS).

RESULTS

Twenty patients completed 52 treatment cycles. Fifteen major events occurred in 7 patients (35 %): 5 events (33 %) related to systemic therapy; 5 (33 %) related to ePIPAC; and 5 (33 %) were biochemical events. No treatment-related deaths occurred. All patients experienced minor events, mostly abdominal pain, nausea and peripheral sensory neuropathy. After treatment, radiological, pathological, cytological, and biochemical response was observed in 0 %, 88 %, 38 %, and 31 % of patients respectively. Curative surgery was achieved in one patient. Median PFS was 10.0 months (95 % confidence interval [CI] 8.0-13.0) and median OS was 17.5 months (95 % CI 13.0-not reached).

CONCLUSIONS

Combining palliative systemic therapy with oxaliplatin-based ePIPAC in patients with unresectable CPM was feasible and showed an acceptable safety profile. Treatment-induced response and survival are promising, yet further research is required to determine the additional value of ePIPAC to systemic therapy.

Mucinous appendiceal neoplasms: Report of a case and brief literature review

INTRODUCTION

Appendiceal tumors are rare neoplasms detected in about 2 % of appendicectomies. The clinical presentation is often unspecific, varying from unspecific abdominal pain or presenting as an acute appendicitis or being asymptomatic.

CASE PRESENTATION

We present a case of a patient presenting as an acute appendicitis with a mucocele, and then classified as HAMN. The patient was treated with initial laparoscopic approach and then conversion in laparotomy with appendectomy. Histology demonstrated a high grade appendiceal mucinous neoplasm limited to submucosa (pT3), with concomitant acute phlegmonous appendicitis. The patient was subsequently sent to a referral center where a right hemicolectomy with HIPEC was performed.

DISCUSSION

HAMN is a rare entity, only recently classified as a new kind of appendiceal mucinous neoplasm. Due to the supposed higher aggressivity, HAMN must be treated as an appendiceal adenocarcinoma. The treatment of this rare entity is not yet well standardized, because of the rarity of this disease.

CONCLUSION

HAMN is a very rare tumor. In the emergency setting, it is mandatory to avoid rupture of the appendix, to minimize the risk of developing pseudomyxoma peritonei. Pathology is essential for further decisions in these patients and plays a very important role in treatment and prognosis.

Analysis of causes and prognostic impact of tube occlusion during hyperthermic intraperitoneal chemotherapy for appendiceal pseudomyxoma peritonei

BACKGROUND

Appendiceal pseudomyxoma peritonei (PMP), a rare tumor from mucinous appendiceal origins, is treated with Cytoreductive Surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC). However, tubing blockages during HIPEC treatment pose a common challenge, impeding the smooth progression of therapy. Few studies to date have explored the incidence and risk factors of tube occlusion during HIPEC in patients with appendiceal PMP, as well as its adverse impact on postoperative complications.

METHODS

From October 2017 to June 2023, a total of 80 patients with appendiceal PMP undergoing combined CRS and HIPEC were included in this study. Tubing blockage events were strictly defined, with patients experiencing blockages during HIPEC treatment allocated to the study group, while those with unobstructed perfusion were assigned to the control group. A comparative analysis was conducted between the two groups regarding post-HIPEC health assessments and occurrence of complications. Risk factors for luminal occlusion during closed HIPEC procedures were identified through univariate and multivariate analysis of data from 303 HIPEC treatments.

RESULTS

Tubing blockages occurred in 41 patients (51.3%). The study group experienced prolonged gastrointestinal decompression time (4.1 ± 3.0 vs. 2.5 ± 1.7 days, P = 0.003) and prolonged time to bowel movement (6.1 ± 2.3 vs. 5.1 ± 1.8 days, P = 0.022) compared to the control group. There was no significant difference in the incidence of complications between the two groups. The 1-year survival rate postoperatively was 97%, and the 3-year survival rate was 81%, with no association found between tubing blockage and poorer survival. Additionally, In 303 instances of HIPEC treatment among these 80 patients, tube occlusion occurred in 89 cases (89/303, 29.4%). Multivariable logistic regression analysis revealed age, diabetes, hypertension, and pathology as independent risk factors for tube occlusion.

CONCLUSION

Tubing blockages are a common occurrence during HIPEC treatment, leading to prolonged postoperative gastrointestinal functional recovery time. When patients are elderly and have concomitant hypertension and diabetes, along with a histological type of low-grade mucinous tumor, the risk of tube occlusion increases. However, this study did not find a significant correlation between tubing blockage and the incidence of postoperative complications or overall patient survival.

A retroperitoneal pseudomyxoma of the appendix: A case report

INTRODUCTION

Retroperitoneal pseudomyxoma (RP) is a rare condition characterized by mucinous tumor growth within the retroperitoneal space, commonly originating from the appendix or other abdominal organs. RP presents with non-specific symptoms such as abdominal pain, bloating, and weight loss, making accurate diagnosis challenging. Due to its rarity and symptom overlap with other conditions, RP requires careful management by a multidisciplinary healthcare team.

CASE PRESENTATION

An 82-year-old female with a three-month history of abdominal pain and an abdominal mass underwent diagnostic imaging, revealing a retroperitoneal cystic mass. Exploratory laparotomy identified gelatinous masses originating from the retrocaecal appendix, which were resected. Histopathological examination confirmed a diagnosis of retroperitoneal pseudomyxoma with mucinous appendicular low-grade cystadenoma as the primary source. The patient had an uneventful postoperative course and remained disease-free at a 12-month follow-up.

DISCUSSION

RP's exact cause is unknown but often originates from the appendix, leading to mucinous fluid accumulation in the retroperitoneal cavity. This condition presents with varied symptoms, including abdominal pain and distension, mimicking other abdominal diseases. Diagnosis involves clinical, radiological, and pathological assessments, with imaging showing characteristic features. Treatment comprises surgical resection, potentially combined with HIPEC, aiming for complete cytoreduction. Prognosis depends on factors like tumor grade, extent, and cytoreduction completeness.

CONCLUSION

Retroperitoneal pseudomyxoma is a rare condition with challenging diagnosis due to its non-specific symptoms. Early recognition, surgical resection, and appropriate adjuvant therapies like HIPEC or chemotherapy can improve outcomes in patients with this uncommon disease.

Transfusion of stored autologous blood in patients with low-grade pseudomyxoma peritonei: A retrospective analysis of its safety and outcome

Background

Pseudomyxoma peritonei is a rare disease that presents as a malignant tumor on the peritoneal surface. Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy is the standard treatment for this disease and frequently requires a red blood cell transfusion. However, due to the limited collection and supply of allogeneic blood, surgical treatment may be delayed due to inadequate preparation of allogeneic blood in the course of clinical treatment. This study aimed to evaluate the safety and efficacy of transfusion of stored autologous blood in patients with low-grade pseudomyxoma peritonei.

Methods

Pseudomyxoma peritonei patients who received cytoreductive surgery combined with heat-infused peritoneal chemotherapy were divided into two groups: transfusion of allogeneic blood and transfusion of stored autologous blood. A comparison of the differences in multiple factors between the two groups was performed, including tumor recurrence, survival time, hemoglobin and hematocrit levels, coagulation function (prothrombin time, activated partial thromboplastin time, and fibrinogen), total hospital stay duration, and incidence of serious adverse events after surgery.

Results

Propensity scores matching analysis yielded 34 patients with allogeneic blood transfusion and 34 patients with stored autologous blood transfusion. Comparison analysis did not show statistical differences in several factors, including age, tumor grade, tumor recurrence rate after surgery, etc., between the two groups. The cytoreductive degree was considered an independent risk factor for tumor recurrence. The pseudomyxoma peritonei patients in the autologous transfusion group had a higher 5-year survival rate and a longer survival time. Moreover, transfusion of stored autologous blood did not increase the rate of tumor recurrence, or the total hospital stay duration after surgery, the hemoglobin level and coagulation function were well stabilized within 24 h after surgery, and there was a low incidence of serious adverse events.

Conclusion

The clinical application of transfusion of stored autologous blood in pseudomyxoma peritonei patients is safe and effective.

Unusual site of pseudomyxoma peritonei recurrence after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy: a case report of intraluminal disease manifestation in the small bowel

BACKGROUND

Pseudomyxoma peritonei (PMP) is an uncommon clinical condition characterized by the presence of mucinous ascites, mainly induced by perforated appendiceal mucinous neoplasms (AMN). The peritoneal surface of the small bowel is usually spared from disease manifestation due to peristaltic movements. Mucinous tumours can disseminate as PMP on the entire peritoneum, but are rarely intraluminal. For the first time in literature, we report a case of intraluminal PMP involving the ileum.

CASE PRESENTATION

A 75-year-old male was treated for perforated AMN and disseminated PMP with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. During follow-up, the patient developed intraperitoneal recurrence together with intraluminal depositions in the ileum, both disease manifestations with identical KRAS and SMAD4 mutations. Hereafter, the patient was treated with palliative care.

CONCLUSION

This case illustrates the variation in the biological and clinical behaviour of this rare disease. Clinicians should be aware of unusual tumour distribution patterns of PMP, including the presence of mucinous tumour within the small bowel.

Appendiceal tumors and pseudomyxoma peritonei: French Intergroup Clinical Practice Guidelines for diagnosis, treatments and follow-up (RENAPE, RENAPATH, SNFGE, FFCD, GERCOR, UNICANCER, SFCD, SFED, SFRO, ACHBT, SFR)

INTRODUCTION

This document is a summary of the French Intergroup guidelines regarding the management of appendicular epithelial tumors (AT) and pseudomyxoma peritonei (PMP) published in March 2020, available on the website of the French Society of Gastroenterology (SNFGE) (www.tncd.org).

METHODS

All French medical societies specialized in the management of AT and PMP collaboratively established these recommendations based on literature until December 2019 and the results of a Delphi vote carried out by the Peritoneal Surface Oncology Group International experts, and graded into 4 categories (A, B, C, Expert Agreement) according to their level of evidence.

RESULTS

AT and PMP are rare but represent a wide range of clinico-pathological entities with several pathological classification systems and different biological behaviors. Their treatment modalities may vary accordingly and range from simple surveillance or laparoscopic appendectomy to complete cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) and / or systemic chemotherapy. The prognosis of these neoplasms may also largely vary according to their pathological grade and spreading at diagnosis or during the follow-up. Given the rarity of certain situations, the therapeutic strategy adapted to each patient, must be discussed in a specialized multidisciplinary meeting after a specialized pathological and radiological pre-therapeutic assessment and a clinical examination by a surgeon specializing in the management of rare peritoneal malignancies.

CONCLUSION

These recommendations are proposed to achieve the most beneficial strategy in a daily practice as the wide range and the rareness of these entities renders their management challenging. These guidelines are permanently being reviewed.

Progression to pseudomyxoma peritonei in patients with low grade appendiceal mucinous neoplasms discovered at time of appendectomy

BACKGROUND

The discovery of a low grade appendiceal mucinous neoplasm (LAMN) during appendectomy is a rare scenario. These neoplasms can progress to pseudomyxoma peritonei (PMP), however the incidence of progression is not well known.

METHODS

The records of all patients with a diagnosis of localized LAMN found during appendectomy were identified, and demographic, tumor, surveillance, and outcome variables were analyzed.

RESULTS

Progression to PMP occurred in 20% of patients in an average of 12.4 months after appendectomy with median follow-up of 18 months. Tumor variables such as margin positivity, appendiceal perforation, and presence of extra-appendiceal acellular mucin or mucinous epithelium on the serosal were not significantly associated with progression.

CONCLUSIONS

During an average follow-up period of 18 months after surgery, progression to PMP occurred in a fifth of patients. It is difficult to predict which patients will progress, therefore cross-sectional imaging surveillance is recommended for all patients.

Pseudomyxoma peritonei of appendiceal origin mimicking ovarian cancer - a case report with literature review

Pseudomyxoma peritonei (PMP) is a rare and uncommon condition, characterized by the presence of mucinous ascites in the abdominal cavity. The most common cause of PMP is mucinous adenocarcinoma of the appendix, followed by neoplasms of the ovary, endocervix, fallopian tube, alimentary organs, urachus, urinary bladder, lung, mucinous cyst of the spleen, and breast.

Herein, we report a case of a 64-year-old postmenopausal woman (gravida 2, para 2) who presented at the department of gynecology with a short history of nausea and abdominal distention. Abdominal and vaginal ultrasonography showed a large amount of free fluid in the pelvis with hyperechoic echogenicity and right pelvic tumor with mixed echogenicity. Computed tomography demonstrated the presence of a heterogeneous, hypodense mass, without contrast enhancement, located on the right side of the pelvis, near the right ovary. Laparotomy was performed. Revision of the abdominal cavity revealed a large amount of yellow gelatinous mucinous ascites – approximately 1.5 l. A tumor (6 x 7 cm in diameter), arising from the appendix and located in the pouch of Douglas near the right ovary, was observed. Histopathology examination revealed poorly differentiated mucinous appendiceal adenocarcinoma, comprising up to 50% signet ring cells.

Gastrointestinal tumors such as appendiceal neoplasms combined with PMP may mimic ovarian carcinomas. Computed tomography, abdominal/vaginal ultrasonography and tumor marker levels (carcino-embryonic antigen, carbohydrate antigen 19.9, carbohydrate antigen Ca-125) may establish the diagnosis.

A differential diagnosis with appendiceal tumors should be considered for patients with right pelvic masses.

Hyperthermic Intraperitoneal Chemotherapy: A Critical Review

Simple Summary

Patients with cancer of the digestive system or ovarian cancer are at risk of developing peritoneal metastases (PM). In some patients with PM, surgery followed by intraperitoneal (IP) chemotherapy has emerged as a valid treatment option. The addition of hyperthermia is thought to further enhance the efficacy of IP chemotherapy. However, the results of recent clinical trials in large bowel cancer have put into question the use of hyperthermic intraperitoneal chemotherapy (HIPEC). Here, we review the rationale and current results of HIPEC for PM and propose a roadmap to further progress.

Abstract

With increasing awareness amongst physicians and improved radiological imaging techniques, the peritoneal cavity is increasingly recognized as an important metastatic site in various malignancies. Prognosis of these patients is usually poor as traditional treatment including surgical resection or systemic treatment is relatively ineffective. Intraperitoneal delivery of chemotherapeutic agents is thought to be an attractive alternative as this results in high tumor tissue concentrations with limited systemic exposure. The addition of hyperthermia aims to potentiate the anti-tumor effects of chemotherapy, resulting in the concept of heated intraperitoneal chemotherapy (HIPEC) for the treatment of peritoneal metastases as it was developed about 3 decades ago. With increasing experience, HIPEC has become a safe and accepted treatment offered in many centers around the world. However, standardization of the technique has been poor and results from clinical trials have been equivocal. As a result, the true value of HIPEC in the treatment of peritoneal metastases remains a matter of debate. The current review aims to provide a critical overview of the theoretical concept and preclinical and clinical study results, to outline areas of persisting uncertainty, and to propose a framework to better define the role of HIPEC in the treatment of peritoneal malignancies.

Lymph node positivity and association with long-term survival for different histologies of appendiceal cancer

BACKGROUND

Appendiceal cancers represent a diverse group of malignancies with varying biological behavior. The significance of lymph node metastases in relation to long-term survival and chemotherapy response is poorly defined.

METHODS

The National Cancer Database was queried to find patients diagnosed with appendiceal cancer from 1998 to 2012. Kaplan-Meier curves and multivariable Cox regression analyses were used to study the association between lymph node status and overall survival. Stage IV patients were excluded.

RESULTS

The rate of nodal positivity of the 9841 patients with known node status was: signet ring 47.4%, carcinoid 42.3%, nonmucinous adenocarcinoma 28.8%, goblet cell 21.9%, and mucinous adenocarcinoma 20.4%. Node-positive patients had worse long-term survival for all subtypes with the exception of carcinoid tumors (p < 0.001). The strongest association was for signet cell and goblet cell. Adjuvant chemotherapy in node-positive patients improved survival for mucinous, nonmucinous, and signet ring cell histology (p < 0.01), but not for goblet cell.

CONCLUSIONS

Nodal involvement in patients with appendiceal cancer varies in incidence, association with adverse survival, and response to systemic therapy. Individualized treatment algorithms for the management of the subtypes of appendiceal cancer are needed.

Risk of appendiceal neoplasm after interval appendectomy for complicated appendicitis: A systematic review and meta-analysis

BACKGROUND

Non-operative management is often the treatment of choice in cases of complicated appendicitis and routine interval appendectomy is not usually recommended. Actually, recent studies show an alarming number of appendiceal neoplasms following interval appendectomy. The aim of this study is to evaluate the prevalence of appendiceal neoplasms and their histological types after interval appendectomy for complicated appendicitis in adults.

METHODS

A comprehensive literature search of the PubMed, Scopus and Web of Science databases was conducted according to the PRISMA statement. Studies reporting appendiceal neoplasm rates after interval appendectomy and histopathological characteristics were included. The most recent World Health Organization (WHO) classification of malignant tumours was considered. A pooled prevalence analysis for both prevalence and pathology was performed.

RESULTS

A total of eight studies was included: seven retrospective series and one randomized controlled trial. The pooled prevalence of neoplasms after interval appendectomy was 11% (95% CI 7-15; I² = 37.5%, p = 0.13). Appendiceal mucinous neoplasms occurred in 43% (95% CI 19-68), adenocarcinoma in 29% (95% CI 6-51), appendiceal neuroendocrine neoplasm in 21% (95% CI 6-36), globet cell carcinoma in 13% (95% CI -2-28), adenoma or serrated lesions in 20% (95% CI -0-41) of cases.

CONCLUSION

The risk of appendiceal neoplasm in patients treated with interval appendectomy for complicated appendicitis is 11%; mucinous neoplasm is the most common histopathological type. Further studies should investigate this association in order to clarify the biological pathway and clinical implications.

Metastatic prostate adenocarcinoma and high-grade appendiceal mucinous neoplasm mimicking acute appendicitis in a post-radiation therapy patient

Prostate cancer is the most common visceral malignancy diagnosed in males. Surveillance for post-treatment neoplasms is very crucial. Here we report the first case of recurrent metastatic prostate cancer presenting as acute appendicitis in a background of a high-grade appendiceal mucinous neoplasm. In addition, this case also includes an unusually early presentation of a secondary primary malignancy after radiation therapy. A 70-year-old male with a history of prostate adenocarcinoma status post-proton radiation therapy presented with recurrent poorly differentiated prostate adenocarcinoma with disease progression and extra-prostatic extension. He underwent salvage proton therapy and testosterone replacement therapy. Two years later, the patient presented with right lower quadrant pain. A computed tomography scan showed perforated acute appendicitis with intra-abdominal abscess, which was treated with interval appendectomy. Upon histologic analysis, metastatic prostatic adenocarcinoma was noted in the appendiceal wall and mesoappendix. In addition, an incidental background of high-grade appendiceal mucinous neoplasm was found. Four months later, he presented with persistent abdominal pain, rapid weight loss, fatigue, and fever for 3 months. An abdominal CT scan revealed a 6.1 cm rectal mass. Pathologic analysis diagnosed an aggressive post-radiation spindle cell sarcoma, intermediate to high grade. The patient opted for palliative care. This case shows that a clinical presentation of acute appendicitis in an older patient may sometimes portend a neoplastic rather than infectious etiology. Clinical history and patient epidemiology should always be considered when evaluating an older patient with clinical signs and symptoms of acute appendicitis.

A rare cecal subepithelial tumor in a Crohn´s Disease patient

Appendiceal tumors comprise a variety of histologic types, including appendiceal mucinous neoplasms, which can be grouped as premalignant lesions, tumors of uncertain malignant potential, and malignant lesions. The appendiceal mucinous neoplasms are characterized by mucinous epithelial proliferation with extracellular mucin and pushing tumor margins, commonly an incidental finding during operative exploration. We report the case of a low-grade appendiceal mucinous neoplasm presenting as a subepithelial lesion in Crohn´s Disease patient. The diagnosis was not straightforward, and only surgical resection allowed an accurate diagnosis. Although Inflammatory Bowel Disease is a risk factor for the development of colorectal neoplasms, the absolute risk for appendiceal tumors is uncertain. The frequency of progression to malignancy remains to be determined.

The Prognostic Impact of Pathology on Patients With Pseudomyxoma Peritonei Undergoing Debulking Surgery: A Systematic Review and Meta-Analysis of Retrospective Studies

Background: Pseudomyxoma peritonei (PMP) is a rare clinical condition with fatal outcomes, which is characterized by the progressive accumulation of mucinous ascites and peritoneal implants. Some studies have reported the effect of PMP biology on patient outcome. The objective of this study was to analyze published articles focusing on the impact of pathology on the prognosis of PMP patients undergoing debulking.

Methods: Data from all studies regarding the prognosis of patients, with different pathologies, who underwent debulking surgery were analyzed. We searched PubMed, the Wiley Online Library, Ovid, and the Cochrane Library (through January 2020). Studies were confined to those articles written in English. Five studies were identified, and the differences in 5-year survival rates were analyzed according to the Kaplan–Meier survival curves. The hazard ratios (HRs) of the 5-year survival rates were calculated.

Results: The mean and median 5-year survival rates of all patients were 39 and 40%, respectively. The median overall survival was 49.3 months. The mean 5-year survival rates of low-grade PMP was 45.2%. The five studies had sufficient data to calculate HRs from the 5-year survival rates data, and three had HRs lower than 1. The total HRs was 0.54, with a 95% CI between 0.33 and 0.89 (P = 0.01).

Conclusions: Among PMP patients receiving debulking surgery who are not able to undergo complete cytoreductive surgery, low-grade biological PMP had a better prognosis than high-grade PMP.

Clinical Implications of Genetic Signatures in Appendiceal Cancer Patients with Incomplete Cytoreduction/HIPEC

INTRODUCTION

Clinical decision-making is challenging in patients who undergo cytoreductive surgery/hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) when complete cytoreduction is not feasible. Nevertheless, some patients still benefit with long-term survival after incomplete CRS/HIPEC. There is currently no robust predictive tool that can assist clinical decision-making in this setting.

METHODS

We quantified gene expression of 79 appendiceal mucinous neoplasms (AMN) from patients with incomplete CRS/HIPEC (R2 resection) using a custom NanoString gene panel. Using our previously defined, prognostic subtype classification algorithm based on signed nonnegative matrix factorization, we classified AMN cases into three molecular subtypes termed: immune enriched (IE), mixed (M), and oncogene enriched (OE). Kaplan-Meier and Cox proportional hazards analyses were used to associate subtypes and individual genes with overall survival (OS).

RESULTS

Median overall survival (OS) was 7.7 years for IE, 3.6 years for M, and 1.4 years for OE. Compared with IE, OE was associated with significantly lower survival [hazard ratio (HR) 3.64, 95% confidence interval (CI) 1.63-8.13; p = 0.0017]. The differences were observed in both low-grade and high-grade tumors. While only two genes were identified to be associated with OS in low-grade tumors, multiple genes were identified to be associated with OS in high-grade tumors, particularly genes with functions in cell cycle/proliferation, mucin production, immune pathways, and cell adhesion/migration.

CONCLUSION

Genetic signatures have prognostic value in patients with incomplete cytoreduction and provide valuable information to assist clinical and operative decision-making. Unraveling genetic alterations and involved pathways can direct efforts to design novel therapeutic modalities.

Intraperitoneal chemotherapy for peritoneal metastases: an expert opinion

Introduction: The rationale for intraperitoneal (IP) drug delivery for patients with peritoneal metastases (PM) is based on the pharmacokinetic advantage resulting from the peritoneal-plasma barrier, and on the potential to adequately treat small, poorly vascularized PM. Despite a history of more than three decades, many aspects of IP drug delivery remain poorly studied.Areas covered: We outline the anatomy and physiology of the peritoneal cavity, including the pharmacokinetics of IP drug delivery. We discuss transport mechanisms governing tissue penetration of IP chemotherapy, and how these are affected by the biomechanical properties of the tumor stroma. We provide an overview of the current clinical evidence on IP chemotherapy in ovarian, colorectal, and gastric cancer. We discuss the current limitations of IP drug delivery and propose several potential areas of progress.Expert opinion: The potential of IP drug delivery is hampered by off-label use of drugs developed for systemic therapy. The efficacy of IP chemotherapy for PM depends on cancer type, disease extent, and mode of drug delivery. Results from ongoing randomized trials will allow to better delineate the potential of IP chemotherapy. Promising approaches include IP aerosol therapy, prolonged delivery platforms such as gels or biomaterials, and the use of nanomedicine.

Mucinous appendiceal adenocarcinomas: a diagnostic challenge

Mucinous appendiceal neoplasms are rare and diagnosis is often difficult as patients present with non-specific symptoms often suggestive of appendicitis only and most diagnoses are made following post-surgery histology examination. Here we present a case of a mucinous appendiceal adenocarcinoma with areas of both Low-grade Appendiceal Mucinous Neoplasm and High-grade Appendiceal Mucinous Neoplasm, in a ruptured appendix at a district general hospital. Without early detection and treatment these pathologies can lead to pseudomyxoma peritonei, a syndrome of progressive mucinous ascites. This case highlights the limitations of radiological studies, benefits of diagnostic laparoscopy and provides a rationale for removing the mesoappendix with the appendix during routine appendectomies.

The prognostic relevance of histologic subtype in appendiceal adenocarcinoma

BACKGROUND

The aim of this population-based study was to determine the prognostic value of the histologic subtypes mucinous (MAC), non-mucinous (AC) and signet ring cell (SRCC) adenocarcinoma among patients with appendiceal cancer.

METHODS AND MATERIALS

Data from the Netherlands Cancer Registry (NCR) of patients with primary appendiceal adenocarcinomas with MAC, AC and SRCC histologic subtype, diagnosed between 2001 and 2015 were used (n = 675). To categorize patients according to the recent histopathological classification, the NCR was linked with the Dutch Pathology Registry (PALGA). Log-rank tests and Kaplan-Meier analyses were performed to estimate overall survival (OS), and the cox proportional hazards model was run to identify prognostic factors.

RESULTS

AC was the most frequently encountered histologic subtype (50.9%), followed by MAC (35.8%) and SRCC (13.3%). In locoregional disease, histologic subtype was not a prognostic factor for OS with 5-year survival rates for patients with AC, MAC and SRCC of 60.0%, 60.5% and 69.6% respectively (p = 0.68). Metastatic disease was more common in SRCC (53.8%) than in MAC (38.8%) and AC (23.4%) (p < 0.0001). Median OS for patients with metastatic disease was 12.6, 27.7 and 18.2 months in AC, MAC and SRCC respectively (p < 0.005). MAC was associated with higher survival compared to AC (HR 0.48, 95%CI 0.34-0.69). In subanalyses, MAC was only a positive prognostic factor compared to AC in patients with peritoneal metastases (HR 0.42, 95%CI 0.28-0.62).

CONCLUSION

Histologic subtype had no prognostic relevance in locoregional or systemic metastatic disease in appendiceal adenocarcinoma. In peritoneal metastases, mucinous histologic subtype was a favorable prognostic factor, compared to non-mucinous and signet ring cell subtype.