Early identification of DPAM in at-risk low-grade appendiceal mucinous neoplasm patients: a new approach to surveillance for peritoneal metastasis

Risk stratification of surveillance for low-grade appendiceal mucinous neoplasms

BACKGROUND

Low-grade appendiceal mucinous neoplasms (LAMNs) can progress to pseudomyxoma peritonei (PMP). The incidence and risk factors for recurrence are unclear, and there is a lack of consensus on the need and duration of surveillance imaging.

METHODS

Patients at the Mayo Clinic in Rochester, Minnesota, with a histologic diagnosis of LAMNs confined to the appendix and limited involvement of the right lower quadrant from 1992 to 2023 were included. Associations between recurrence and risk factors were assessed using Kaplan-Meier curves and Cox proportional hazards regression.

RESULTS

A total of 125 patients with LAMNs underwent abdominal imaging surveillance for a median of 51.2 months (IQR, 26-92). Of note, 5 patients (4%) recurred, all of which were PMP. Overall, the 5- and 10-year cumulative recurrence incidence rates were 3% and 6%, respectively. The median time to recurrence was 24 months (IQR, 23-87). Only LAMNs limited to the right lower quadrant and LAMN tumor size of <2 cm were associated with recurrence (P < .05). The 5- and 10-year cumulative recurrence risks were 12% and 30%, respectively, for the 21 patients with either risk factor. Only 1% of patients without these 2 risk factors developed a recurrence at 10 years.

CONCLUSION

The overall recurrence risk of LAMN after resection is low. Appendectomy is sufficient for LAMN. Select patients with acellular mucin confined to the right lower quadrant and a tumor size of <2 cm are at higher risk of recurrence. Thus, long-term surveillance is recommended for high-risk individuals. Conversely, LAMNs without risk factors can be safely observed expectantly.

Exploring the mysterious mucinous appendiceal neoplasm

Mucinous neoplasms of the appendix comprise a group of diagnostically challenging lesions that have generated significant controversy and confusion throughout the years, given their potential for aggressive behavior despite very bland cytologic features. Numerous classification schemes have been proposed to characterize and stage these lesions, but confusion remains among pathologists, surgeons, and oncologists regarding diagnostic criteria, therapeutic implications, and overall prognosis. This review summaries the current recommended nomenclature, histologic characteristics of each entity, and helpful features to distinguish neoplasia from benign mimics.

What is the optimum post treatment surveillance imaging protocol for low-grade appendiceal mucinous neoplasms and pseudomyxoma peritoneii?

Appendiceal mucinous neoplasms are rare and can be associated with the development of disseminated peritoneal disease known as pseudomyxoma peritonei (PMP). Mucinous tumours identified on appendicectomy are therefore followed up to assess for recurrence and the development of PMP. In addition, individuals who initially present with PMP and are treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) are followed up to assess for recurrence. However, despite the concerted efforts of multiple expert groups, the optimal imaging follow-up protocol is yet to be established. The purpose of this article is to review the available evidence for imaging surveillance in these populations to identify the optimum post-resection imaging follow-up protocol.

Neoplastic appendiceal mucinous lesions: a narrative review of the literature from an oncologist's perspective

Appendiceal mucinous lesions' classification and nomenclature has been modified several times along the last decades, reflecting their great heterogeneity and making difficult to compare results and draw conclusions. Despite its nearby origin, appendiceal mucinous lesions have a distinctive behaviour compared to colorectal cancer, including their molecular and genetic markers. Due to their low frequency, their management is not well standardised. However, surgery is considered the cornerstone of treatment. Their indolent behaviour has encouraged surgeons to apply more aggressive treatments, such as cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC), that may extend overall survival. Chemotherapy is reserved for unresectable and/or disseminated disease and could play a role in the adjuvant and neoadjuvant setting. Pressurised intraperitoneal aerosol chemotherapy (PIPAC) is recently emerging as a possible alternative for treatment in advanced disease although its results in long-term survival are lacking Hereby, we review the available evidence in the management of appendiceal mucinous lesions, including localised and disseminated disease, with a special emphasis on the oncological perspective, focusing on the lights and shadows of the systemic treatments.

Appendiceal Mucinous Neoplasms and Inflammatory Bowel Disease: Systematic Review of the Literature

There is no clear evidence on the prevalence and clinical presentation of appendiceal mucinous neoplasm (AMN) among patients with inflammatory bowel disease (IBD), so a systematic review was performed to investigate the diagnosis, management and treatment of AMN in these patients. PubMed, Medline, Scopus and the Cochrane Library were searched for articles published up to September 2023. Twenty-three studies reporting data about 34 AMN patients were included. UC patients had a median age of 52 years and a median length of disease of 10 years; CD patients had a median age of 40.5 years and a median length of disease of 5 years. A pre-operative diagnosis was achieved in 44% of patients. Most patients were symptomatic (82.6%) and showed moderate-severe disease activity (61%). Surgical procedures were performed: laparoscopic appendectomy, ileocecal resection, right hemicolectomy and colectomy/proctocolectomy. Of the patients, 73.5% were diagnosed with low-grade mucinous neoplasm (LAMN) and nine with adenocarcinoma. Synchronous colorectal dysplasia/carcinoma was present in 23.5% of patients. IBD patients with long-standing disease should be routinely screened, not only for colorectal cancer but also for AMN, during gastro-enterologic follow-up. Laparoscopic appendectomy of unruptured LAMN as well as right hemicolectomy of non-metastatic adenocarcinoma are safe procedures in IBD patients.

Neoplasms of the Appendix

BACKGROUND

Neoplasms of the vermiform appendix are rare. They comprise a heterogeneous group of entities requiring differentkinds of treatment.

METHODS

This review is based on publications retrieved by a selective literature search in the PubMed, Embase, and Cochranedatabases.

RESULTS

0.5% of all tumors of the gastrointestinal tract arise in the appendix. Their treatment depends on their histopathologicalclassification and tumor stage. The mucosal epithelium gives rise to adenomas, sessile serrated lesions, adenocarcinomas,goblet-cell adenocarcinomas, and mucinous neoplasms. Neuroendocrine neoplasms originate in neuroectodermal tissue. Adenomasof the appendix can usually be definitively treated by appendectomy. Mucinous neoplasms, depending on their tumorstage, may require additional cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemoperfusion (HIPEC). Adeno -carcinomas and goblet-cell adenocarcinomas can metastasize via the lymphatic vessels and the bloodstream and should thereforebe treated by oncological right hemicolectomy. Approximately 80% of neuroendocrine tumors are less than 1 cm in diameterwhen diagnosed and can therefore be adequately treated by appendectomy; right hemicolectomy is recommended if the patienthas risk factors for metastasis via the lymphatic vessels. Systemic chemotherapy has not been shown to be beneficial forappendiceal neoplasms in prospective, randomized trials; it is recommended for adenocarcinomas and goblet-cell adenocarcinomasof stage III or higher, in analogy to the treatment of colorectal carcinoma.

Incidence and outcomes of delayed presentation and surgery in peritoneal surface malignancies

Background

Peritoneal surface malignancies (PSM) present insidiously and often pose diagnostic challenges. There is a paucity of literature quantifying the frequency and extent of therapeutic delays in PSM and its impact on oncological outcomes.

Methods

A review of a prospectively maintained registry of PSM patients undergoing Cytoreductive Surgery and Hyperthermic Intra-peritoneal Chemotherapy (CRS-HIPEC) was conducted. Causes for treatment delays were identified. We evaluate the impact of delayed presentation and treatment delays on oncological outcomes using Cox proportional hazards models.

Results

319 patients underwent CRS-HIPEC over a 6-years duration. 58 patients were eventually included in this study. Mean duration between symptom onset and CRS-HIPEC was 186.0 ± 37.1 days (range 18-1494 days) and mean duration of between patient-reported symptom onset and initial presentation was 56.7 ± 16.8 days. Delayed presentation (> 60 days between symptom onset and presentation) was seen in 20.7% (n=12) of patients and 50.0% (n=29) experienced a significant treatment delay of > 90 days between 1^st presentation and CRS-HIPEC. Common causes for treatment delays were healthcare provider-related i.e. delayed or inappropriate referrals (43.1%) and delayed presentation to care (31.0%). Delayed presentation was a significantly associated with poorer disease free survival (DFS) (HR 4.67, 95% CI 1.11-19.69, p=0.036).

Conclusion

Delayed presentation and treatment delays are common and may have an impact on oncological outcomes. There is an urgent need to improve patient education and streamline healthcare delivery processes in the management of PSM.

Significance of laparoscopic cytoreductive surgery for appendiceal pseudomyxoma peritonei with limited disease and low tumor burden

OBJECTIVE

To investigate the clinical value of laparoscopic cytoreductive surgery (CRS) in treating of appendiceal pseudomyxoma peritonei with limited disease and low tumor burden.

METHODS

The clinical data of patients with appendiceal pseudomyxoma peritonei treated by surgery with CRS at the Aerospace Center Hospital from January 2018 to December 2021 were retrospectively analyzed. The patients were divided into laparoscopic or open CRS groups according to the operation method. A propensity score-matched (PSM) analysis (1:1) was performed, the related clinical variables were compared between the two groups, and the effect on progression-free survival (PFS) was also analyzed.

RESULTS

One hundred and eight patients were included in this study. After PSM, 33 patients were selected from each group and the age and peritoneal cancer index were matched between the two groups. There were significant differences in operation time (P < 0.001), intraoperative bleeding (P < 0.001), intraoperative blood transfusion (P = 0.007), hospital stay (P < 0.001). The analysis of PFS showed that there was no significant difference between the two operation methods. After multivariate analysis, the pathologic subtype (P = 0.012) was identified as an independent prognostic factor for PFS.

CONCLUSION

The curative effect of laparoscopic CRS is like that of open operation, which can significantly shorten the operation time and hospital stay and reduce intraoperative bleeding and blood transfusion event. The laparoscopic CRS is safe and feasible in strictly selected patients. The pathologic subtype is an independent factor affecting the prognosis for PFS.

The appendix "mucocoele" misnomer: radiological terminology of "likely appendix mucinous neoplasm" better reflects pathology findings

AIM

To review the radiological terminology used to describe dilated mucin-containing appendiceal lesions with correlation to the histopathological diagnosis.

MATERIALS AND METHODS

Radiology and histopathology reports for all patients with an abnormally dilated appendix referred to a tertiary peritoneal malignancy centre, between January 2021 and December 2021, were reviewed.

RESULTS

Overall, 213 patients were included with a median appendiceal diameter of 25.5 mm (range 10-125 mm). Peritoneal disease was present in 109 patients, with the remaining 104 cases demonstrating a dilated appendix only. Local radiology reports were available for 201 cases with the appendix described in 168 cases as appendiceal mucocoele (n=104), appendiceal neoplasm (n=40), appendicitis (n=18), and dilated appendix (n=6). The appendix was not mentioned in 33/201 (15%), either misinterpreted as other pathology (n=15) or not reported (n=18). Peritoneal malignancy histopathology reports were available in 188 cases and reported as low-grade appendix mucinous neoplasm (LAMN, n=144), high-grade appendix mucinous neoplasm (HAMN, n=13), LAMN with foci of HAMN (n=2), LAMN with neuroendocrine tumour (n=2), LAMN with goblet cell adenocarcinoma (n=1), goblet cell adenocarcinoma (n=8), mucinous adenocarcinoma (n=14), non-mucinous adenocarcinoma (n=1), and benign histology (n=3). Only one case of a true inflammatory "mucocoele"/retention cyst was reported.

CONCLUSION

In this cohort of patients, the overwhelming majority of dilated, mucin-filled appendices contained malignant cells and benign mucin-filled appendices were rare. The present authors advocate that the term "likely appendix mucinous neoplasm" should replace "appendix mucocoele" to represent the most likely pathology and facilitate less ambiguous interpretation in management decisions.

[Current treatment recommendations for pseudomyxoma peritonei]

BACKGROUND

The term pseudomyxoma peritonei (PMP) describes a clinical syndrome characterized by the presence of gelatinous intraperitoneal accumulation of mucus. It mostly originates from a mucocele of the vermiform appendix. Affected patients are often asymptomatic for a long time. Because of its indolent nature it is usually diagnosed at an advanced stage. Clinical presentation is determined by the dissemination of the tumor.

METHOD

A search and analysis of the current literature were carried out.

RESULTS

Based on the morphological characteristics PMP subtypes with various malignant potential can be differentiated. The prognosis depends on the histopathological differentiation and the clinical stage. The treatment spectrum varies from laparoscopic appendectomy to complete cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC).

CONCLUSION

Due to the rarity of PMP there are no prospective randomized studies. Therefore, there is still controversy regarding the best stage-dependent treatment strategy. This review article attempts to clarify the optimal management of mucinous neoplasms of the appendix and PMP taking the clinical presentation and the histological differentiation into consideration.

Retrospective Review of Outcomes in Non-Invasive Mucinous Appendiceal Neoplasms with and without Peritoneal Spread: A Cohort Study

Patients treated surgically for local non-invasive mucinous appendiceal neoplasm (NI-MAN) may recur with the development of peritoneal dissemination (PD). The risk of recurrence and predictive factors are not well studied. Patients with NI-MAN, with or without peritoneal dissemination at presentation, were included. Patients with limited disease underwent surgical resection only. Patients with peritoneal dissemination underwent cytoreductive surgery (CRS) with or without hyperthermic intraperitoneal chemotherapy (HIPEC). Patients without PD (nPD) were compared to those who presented with PD. Thirty-nine patients were included, 25 in nPD and 14 in PD. LAMN was diagnosed in 96% and 93% of patients in nPD and PD, respectively. Acellular mucin on the peritoneal surface was seen in 16% of nPD patients vs. 50% of PD patients (p = 0.019). Two (8%) patients in the nPD group who had LAMN without wall rupture recurred, at 57 and 68 months, with a PCI of 9 and 22. The recurrence rate in the PD group was 36%. All recurred patients underwent CRS+HIPEC. A peritoneal recurrence is possible in NI-MANs confined to the appendix even with an intact wall at initial diagnosis. The peritoneal disease may occur with significant delay, which is longer than a conventional follow-up.

Clinicopathologic parameters and outcomes of mucinous neoplasms confined to the appendix: a benign entity with excellent prognosis

Appendiceal mucinous neoplasms (AMNs), characterized by expansile or "pushing" growth of neoplastic epithelium through the appendix wall, are sometimes accompanied by peritoneal involvement, the extent and grade of which largely determine clinical presentation and long-term outcomes. However, the prognosis of tumors entirely confined to the appendix is still debated and confusion remains regarding their biologic behavior and, consequently, their clinical management and even diagnostic nomenclature. We evaluated AMNs limited to the appendix from 337 patients (median age: 58 years, interquartile range (IQR): 47-67), 194 (57.6%) of whom were women and 143 (42.4%) men. The most common clinical indication for surgery was mass or mucocele, in 163 (48.4%) cases. Most cases (N = 322, 95.5%) comprised low-grade epithelium, but there were also 15 (4.5%) cases with high-grade dysplasia. Lymph nodes had been harvested in 102 (30.3%) cases with a median 6.5 lymph nodes (IQR: 2-14) per specimen for a total of 910 lymph nodes examined, all of which were negative for metastatic disease. Histologic slide review in 279 cases revealed 77 (27.6%) tumors extending to the mucosa, 101 (36.2%) to submucosa, 33 (11.8%) to muscularis propria, and 68 (24.4%) to subserosal tissues. In multivariate analysis, deeper tumor extension was associated with older age (p = 0.032; odds ratio (OR): 1.02, 95% confidence intervals (CI): 1.00-1.03), indication of mass/mucocele (p < 0.001; OR: 2.09, CI: 1.41-3.11), and wider appendiceal diameter, grossly (p < 0.001; OR: 1.61, CI: 1.28-2.02). Importantly, among 194 cases with at least 6 months of follow-up (median: 56.1 months, IQR: 24.4-98.5), including 9 high-grade, there was no disease recurrence/progression, peritoneal involvement (pseudomyxoma peritonei), or disease-specific mortality. These data reinforce the conclusion that AMNs confined to the appendix are characterized by benign biologic behavior and excellent clinical prognosis and accordingly suggest that revisions to their nomenclature and staging would be appropriate, including reverting to the diagnostic term mucinous adenoma in order to accurately describe a subset of them.

Recurrence of initially localized appendiceal mucinous neoplasms after radical resection: survey analysis and literature review

BACKGROUND

Appendiceal mucinous neoplasm (AMN) is a rare tumor that may be successfully treated by appendectomy. However, some patients develop recurrence as pseudomyxoma peritonei. The present study investigated the recurrence rate after radial resection for AMN.

METHODS

A survey on AMN was sent to 171 institutions, and 286 cases were analyzed. The risk of recurrence was assessed according to clinical parameters. Recurrence rates were compared with data from the literature.

RESULTS

There were 250 cases in the low-grade group and 36 in the high-grade group, with perforation being detected in 50 cases. After a median follow-up period of 30 months, recurrence was detected in 17 cases, including 12 with high-grade histology and 10 with perforation. Two patients with low-grade histology and no perforation developed recurrence. Independent prognostic factors for recurrence were high-grade histology (p = 0.0001, RR = 8.56) and perforation (p = 0.0168, RR = 3.45). Four groups were classified by histology and perforation: group A: high-grade, perforation ( +), group B: high-grade, perforation (-), group C: low-grade, perforation ( +), group D: low-grade, perforation (-). Five-year recurrence rates in groups A, B, C, and D were 46.7, 25.9, 13.3, and 1.5%, respectively. All cases of recurrence were detected within 3 years, except for two in group B.

CONCLUSIONS

Recurrence in cases with low-grade histology and no perforation was rare; however, a postoperative survey for at least 3 years is required. In contrast, cases with high-grade histology or perforation need to be monitored using a similar approach to colon cancer. Prophylactic CRS + HIPEC may be considered.

Prognostic Significance of Preoperative Tumor Markers in Pseudomyxoma Peritonei from Low-Grade Appendiceal Mucinous Neoplasm: a Study from the US HIPEC Collaborative

BACKGROUND

Tumor markers are commonly utilized in the diagnostic evaluation, treatment decision making, and surveillance of appendiceal tumors. In this study, we aimed to determine the prognostic significance of elevated preoperative tumor markers in patients with pseudomyxoma peritonei secondary to low-grade appendiceal mucinous neoplasm who underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

METHODS

Using a multi-institutional database, eligible patients with measured preoperative tumor markers [carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA 19-9), or cancer antigen 125 (CA-125)] were identified. Univariate and multivariate Cox-proportional hazards regression analysis assessed relationships between normal and elevated serum tumor markers with progression-free and overall survival in the context of multiple clinicopathologic variables.

RESULTS

zTwo hundred and sixty-four patients met criteria. CEA was the most commonly measured tumor marker (97%). Patients who had any elevated tumor marker had a higher peritoneal carcinomatosis index (PCI) as compared to those with normal range markers. Elevated CEA and CA 19-9 levels were individually associated with longer inpatient length of stay, requirement for intraoperative transfusion, and incomplete cytoreduction. Utilization of neoadjuvant chemotherapy, increased PCI score, elevated CA 19-9 (p = 0.007), and CA-125 levels (p = 0.01) were predictive of decreased progression-free survival on univariate analysis. However, in a multivariate model, only elevated PCI was a statistically significant predictor of progression-free survival.

CONCLUSION

Elevated preoperative tumor markers indicate a higher burden of disease but are not independently associated with survival in this retrospective multi-institutional cohort. Further prospective studies are needed to clarify the utility of these markers in this patient population.

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.

Laparoscopic cytoreductive surgery and HIPEC in LAMN with small volume of peritoneal disease: a valuable option of treatment for good patient-related experience measures (PREMs)

BACKGROUND

Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is the best effective treatment for pseudomyxoma peritonei (PMP). In the last years, the advances in histopathology have stratified PMP lesions in different degrees of aggressivity suggesting the possibility of a tailored treatment. In a subset of patients with small volume peritoneal disease, laparoscopic CRS and HIPEC is feasible. The aim of this study is to analyze the results of laparoscopic CRS + HIPEC in a monocentric series of patients under patient-related experience measures (PREMs).

METHODS

All consecutive patients who underwent laparoscopic CRS-HIPEC with curative intent at Cancer Institute of Montpellier were retrieved from a prospectively maintained database and analyzed. Selection criteria for laparoscopic approach were low-grade PMP with pathological confirmation prior to CRS-HIPEC, age < 75 years, no extra-peritoneal disease, peritoneal cancer index (PCI) < 10, and a limited history of abdominal surgery. A PREMS interview was conducted before analysis with all the included patients. Outcomes of interest included postoperative morbidity, medium-term survival, and PREMs.

RESULTS

Fourteen patients were operated on for low-grade PMP with a laparoscopic approach at our institution. Conversions to laparotomy were necessary in three patients, and postoperative complications were observed in three patients (Clavien 3b in one patient). In-hospital postoperative median stay was 9.5 days. No death or recurrence was observed during the study period.

CONCLUSIONS

Laparoscopic CRS-HIPEC for LAMN in presence of small peritoneal disease is feasible in terms of postoperative morbidity and mortality. According to our PREMs questionnaire, patients' expectations were satisfied.

Novel Perspectives in Pseudomyxoma Peritonei Treatment

Simple Summary

Pseudomyxoma Peritonei (PMP) represents a rare entity which greatly benefits from Cytoreductive Surgery (CRS) associated with Hyperthermic Intraperitoneal Chemotherapy (HIPEC). In fact, CRS-HIPEC represents the treatment with potential chances of cure and long-term disease control of patients affected by PMP. This therapeutic strategy should be performed in referral centers, where a consolidated know-how of this locoregional treatment and a multidisciplinary approach are available. CRS-HIPEC provides excellent results for PMP patients in terms of postoperative outcome, overall and disease-free survival, and quality of life. However, in patients with an extensive or recurrent disease, few therapeutic opportunities are available. This review is focused on the most recent clinical evidence and provides a better understanding of the molecular prognostic factors and potential therapeutic targets in this rare malignancy.

Abstract

Pseudomyxoma Peritonei (PMP) is an anatomo-clinical condition characterized by the implantation of neoplastic cells on peritoneal surfaces with the production of a large amount of mucin. The rarity of the disease precludes the evaluation of treatment strategies within randomized controlled trials. Cytoreductive Surgery (CRS) combined with Hyperthermic Intraperitoneal Chemotherapy (HIPEC) has proven to be the only therapeutic option with potential chances of cure and long-term disease control. The present review discusses the epidemiology, pathogenesis, clinical presentation and treatment of PMP, focusing on the molecular factors involved in tumor progression and mucin production that could be used, in the upcoming future, to improve patient selection for surgery and to expand the therapeutic armamentarium.

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.

A Multi-institutional Study of Peritoneal Recurrence Following Resection of Low-grade Appendiceal Mucinous Neoplasms

BACKGROUND

Peritoneal dissemination of low-grade appendiceal mucinous neoplasms (LAMNs), sometimes referred to as pseudomyxoma peritonei, can result in significant morbidity and mortality. Little is known about the natural history of localized (non-disseminated) LAMNs.

OBJECTIVE

The goal of this study was to evaluate the risk of peritoneal recurrence in patients with localized LAMNs.

METHODS

We performed a multi-institutional retrospective review of patients with pathologically confirmed localized LAMNs. Baseline characteristics, pathology, and follow-up data were collected. The primary endpoint was the rate of peritoneal recurrence.

RESULTS

We identified 217 patients with localized LAMNs. Median age was 59 years (11-95) and 131 (60%) patients were female. Surgical management included appendectomy for 124 (57.1%) patients, appendectomy with partial cecectomy for 26 (12.0%) patients, and colectomy for 67 (30.9%) patients. Pathology revealed perforation in 46 patients (37.7% of 122 patients with perforation status mentioned in the report), extra-appendiceal acellular mucin (EAM) in 49 (22.6%) patients, and extra-appendiceal neoplastic cells (EAC) in 13 (6.0%) patients. Median follow-up was 51.1 months (0-271). Seven (3.2%) patients developed a peritoneal recurrence, with a median time to recurrence of 14.4 months (2.5-47.0). Seven (15.2%) patients with histologic evidence of perforation had recurrence, versus no patients (0%) without perforation (p < 0.001); five (10.2%) patients with EAM versus two (1.2%) patients without EAM (p = 0.007), and one (7.7%) patient with EAC versus six (2.9%) patients without EAC (p = 0.355) had recurrence.

CONCLUSIONS

This multi-institutional study represents the largest reported series of patients with localized LAMNs. In the absence of perforation or extra-appendiceal mucin or cells, recurrence was extremely rare; however, patients with any of these pathologic findings require careful follow-up.

Updated staging and patient outcomes in low-grade appendiceal mucinous neoplasms

Low-grade appendiceal mucinous neoplasms (LAMNs) exhibit drastically different clinical course and prognosis depending on tumor stage, particularly as it relates to the extent and cellularity of peritoneal involvement. In this context, recent changes in staging guidelines have sought to clarify criteria for pT and pM categories. This study's aim was to identify clinicopathological features associated with patient outcomes, especially as they pertain to updated stage groups. We reviewed LAMNs from 192 patients (mean age: 56.9 years, 119 (62.0%) women). The tumors consisted of 66 (34.4%) pTisM0, 16 (8.3%) pT3M0, 16 (8.3%) pT4aM0, 27 (14.1%) pTxM1a, and 67 (34.9%) pTxM1b cases. In multivariate analysis, only gross perforation was significantly associated with higher TNM group stage (p = 0.001; OR 3.3, 95% CI: 1.7-6.4). Of 165 (85.9%) patients with clinical follow-up, 51 (30.9%) had disease progression (over a mean 33.7 months, range: 4.7-121.7), whereas over significantly longer follow-up (mean 48.7 months, range: 3.1-143.9; p = 0.004), 114 (69.1%) patients did not. In multivariate analysis, higher TNM stage was significantly associated with disease progression (p = 0.029; OR 18.3, 95% CI: 1.4-246.0). In Kaplan-Meier analysis, none of 74 patients with disease limited to the appendix (pM0), 6 of 27 (22.2%) cases with peritoneal involvement by acellular mucin only (pM1a), and 45 of 64 (70.3%) tumors with intraperitoneal deposits containing neoplastic cells (pM1b) showed disease progression (p < 0.001). These differences in progression-free survival among TNM groups persisted when limiting the analysis to patients who had undergone successful cytoreductive surgery (p = 0.050). Finally, in four patients (all with pM1b disease) death was attributed to disease progression whereas there was no disease-specific mortality in the pM0 and pM1a groups (p = 0.020). These data support the designation of LAMNs with acellular peritoneal mucin as having an intermediate prognosis between cases limited to the appendix and those with intraperitoneal deposits containing neoplastic epithelium.

Laparoscopic hyperthermic intraperitoneal chemotherapy for appendiceal tumors

INTRODUCTION

The application of hyperthermic intraperitoneal chemotherapy (HIPEC) in colorectal and appendix cancer at risk of peritoneal seeding is an appealing strategy to prevent peritoneal metastases. Here, we present the technical details and postoperative outcomes of laparoscopic HIPEC performed with prophylactic intent in three patients with low-grade appendiceal neoplasm (LAMN) considered at risk of peritoneal recurrence.

MATERIALS AND SURGICAL TECHNIQUE

Three patients with LAMN previously treated outside our department were selected for second-look laparoscopic exploration and HIPEC. The study received institutional review board approval. A Hasson trocar was inserted around the umbilicus. Four additional 10-mm trocars were inserted-one each in the left and right upper and lower quadrants. After full abdominal exploration, laparoscopic cytoreductive surgery was performed. Perfusion catheters were inserted through the four lateral trocars in the abdominal quadrants. HIPEC was performed with mitomycin 12 mg/m² and cisplatin 90 mg/m² for 60 minutes at a target temperature of 41.0°C. The postoperative course was uneventful, except for an episode of fluid leak due to dural tear (treated with supine bed rest for 48 hours and resulting in no adverse sequelae). The median length of hospital stay was 11 days. After a median follow-up of 36 months, all patients were asymptomatic with no evidence of recurrence.

DISCUSSION

Laparoscopic HIPEC for LAMN at risk of peritoneal recurrence appeared to be feasible, safe, and associated with a favorable postoperative outcome. More studies with larger samples of patients and with a standardized design are needed to better analyze the oncological value of this approach.

Comparative effectiveness of prophylactic hyperthermic intraperitoneal chemotherapy (HIPEC) for resected low-grade appendiceal mucinous neoplasm (LAMN): A protocol for systematic review and network meta-analysis

BACKGROUND

Whether prophylactic hyperthermic intraperitoneal chemotherapy (HIPEC) offers long-term survival benefit to patients with low-grade appendiceal mucinous neoplasms (LAMNs) after resection surgery is still under heated debate. The aim of the present meta-analysis is to investigate the comparative effectiveness and safety of prophylactic HIPEC regimens in LAMNs METHODS:: A systematic search of MEDLINE, EMBASE, PubMed, Web of Science, the Cochrane Central Register of Controlled Trials, International Clinical Trials Registry Platform (ICTRP), clinicaltrials.gov and controlledtrials.com will be performed. All published RCTs and quasi-RCTs through July 20, 2020 with language restricted in English will be included in this review study. Two reviewers will independently conduct the procedures of study identification, data collection, and methodological quality assessment. The primary outcomes are overall survival (OS) and disease-free survival (DFS). The secondary outcomes consist of peritonitis and sepsis, colonic fistula, chemotherapy-associated adverse events, and adhesive intestinal obstruction. The pooled odds ratios (ORs) or hazard ratios (HRs) and relative 95% confident intervals (CIs) of each outcome measurement will be calculated. EndNote X9 software will be applied to manage all citations. The Stata software version 14.0 and R x64 software version 3.5.1 will be employed for main statistical analyses.

DISCUSSION

This study will employ a network meta-analysis to summarize direct and indirect evidence in the specific area to provide detailed individualized guidance on surgical management for LAMNs.

REGISTRATION

This protocol was registered with the International Platform of Registered Systematic Review and Meta-Analysis Protocols (INPLASY) on 25 July 2020 (registration number INPLASY202070112).

Surgical management of appendiceal mucinous neoplasm: Is appendectomy sufficient?

BACKGROUND AND OBJECTIVES

Due to the rarity of appendiceal mucinous neoplasms (AMNs), there are few established treatment guidelines. The clinical course varies from incidental detection to progressive spread with pseudomyxoma peritonei (PMP). This study investigated the extent of resection on the prognosis and outcomes of AMNs.

METHODS

This multicenter retrospective study evaluated patients with AMN who underwent surgery between 4/2006 to 9/2017. Primary endpoints included overall survival (OS) and disease-specific survival (DSS). Secondary endpoints included PMP incidence and treatment with cytoreductive surgery (CRS).

RESULTS

Of the 138 patients with AMN, 70 patients (54%) underwent appendectomy, 26 (19%) cecectomy, and 37 (27%) right hemicolectomy. The median age was 59.7 years and 57 patients (41%) were male. Males were less likely to undergo cecectomy (P = .03). Rupture rates, tumor characteristics, and incidence of PMP were similar across surgery groups. Median follow-up was 61.3 months. Five-year OS and DSS for the total cohort were 94.9% and 98.6%, respectively, and remained similar across all surgery groups. CRS patients were more likely to undergo right hemicolectomy with no difference in survival by surgery type (P = .03).

CONCLUSIONS

Patients with AMN have a good overall prognosis and there may be minimal benefit to performing extended surgical resection in these patients.

Zap it track it: the application of Lean Six Sigma methods to improve the screening system of low-grade mucinous neoplasms of the appendix in an acute hospital setting

OBJECTIVE

To improve the number of patients receiving annual computed tomography (CT) scan and tumour markers, who are diagnosed with low-grade mucinous neoplasms (LAMN).

DESIGN

A pre-/post-intervention design was employed using Lean Six Sigma methods to identify gaps in the screening system and to develop and implement solutions for a more robust, auditable screening programme.

SETTING

The patients diagnosed with LAMN of the appendix referred to the acute hospital and are enrolled in the screening service.

PARTICIPANTS

Consultant colorectal surgeons, cancer nurse specialist, colorectal medical team and quality improvement staff.

INTERVENTIONS

Diagnostic tools identified gaps in the current process. A set of improvements were implemented to standardize the pathway for referral and surveillance of patients, provide information on the condition and treatment and standardize and track information received by patients and their referring hospital.

MAIN OUTCOME MEASURE(S)

Pre and post-intervention outcome measures were taken for the number of patients who receive an annual CT of thoracic, abdomen and peritoneum and tumour markers and number of patients who receive information and contact details.

RESULTS

At baseline, of the 28 patients that met the inclusion criteria only 61% had a correct follow-up. Following the implementation of improvements, 78% of patients had correct follow-up and 90% had received information.

CONCLUSIONS

Gaps in the current cancer screening system were identified and improvements implemented a reduced number of patients having an incorrect follow-up. Findings are applicable across all precancerous screening systems irrespective of the type of malignancy. The methods used empowered patients and fostered an interdisciplinary team approach to care.

Impact of Mucin Cellularity and Distribution on Survival in Newly Diagnosed Patients with Low-Grade Appendiceal Mucinous Neoplasm Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

BACKGROUND

Low-grade appendiceal mucinous neoplasms (LAMN) are tumors that frequently present with peritoneal spread of either acellular mucin (AM) or cellular mucin (CM). We aim to determine how mucin types and distribution affect survival. PATIENTS AND METHODS: A retrospective cohort study was conducted using a prospective database. Newly diagnosed LAMN patients with AM versus CM treated with cytoreductive surgery/hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) were compared. Postoperative pathology reports were reviewed to assess each involved abdominal zone. Survival was analyzed using the Kaplan-Meier method.

RESULTS

Of 121 identified patients, 50 (41%) had peritoneal lesions with AM and 71 (59%) with CM. Peritoneal cancer index was lower in AM versus CM (mean: 19 ± 13 vs 28 ± 10, p = 0.004), but complete cytoreduction (CC) rates were similar (98% vs 96%, p = 0.642). The 5-year progression-free survival (PFS) was higher in AM versus CM (96% vs 69.8%, p = 0.002). CM patients had zones with both types of lesions: with and without cells. The CM subgroup analysis showed significant differences in 5-year progression-free survival (PFS) among patients with 1-3, 4-7, and 8-10 zones with cells (95.2%, 68.4%, and 35.7%, respectively, p < 0.001), but PFS was not affected by the number of zones with any lesion type. There was no difference in overall survival (OS) between groups.

CONCLUSIONS

Despite comparable CC rates after CRS/HIPEC, CM patients have shorter PFS than AM patients. In CM patients, more zones with cells, but not the total number of involved zones, negatively impact PFS. Mucin type does not impact OS. It is important to assess and report mucin cellularity in LAMN specimens.

Appendiceal tumours and pseudomyxoma peritonei: Literature review with PSOGI/EURACAN clinical practice guidelines for diagnosis and treatment

Pseudomyxoma Peritonei (PMP) is a rare peritoneal malignancy, most commonly originating from a perforated epithelial tumour of the appendix. Given its rarity, randomized controlled trials on treatment strategies are lacking, nor likely to be performed in the foreseeable future. However, many questions regarding the management of appendiceal tumours, especially when accompanied by PMP, remain unanswered. This consensus statement was initiated by members of the Peritoneal Surface Oncology Group International (PSOGI) Executive Committee as part of a global advisory role in the management of uncommon peritoneal malignancies. The manuscript concerns an overview and analysis of the literature on mucinous appendiceal tumours with, or without, PMP. Recommendations are provided based on three Delphi voting rounds with GRADE-based questions amongst a panel of 80 worldwide PMP experts.

Laparoscopic cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for perforated low-grade appendiceal mucinous neoplasms

Introduction

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is an established treatment for pseudomyxoma peritonei (PMP) from perforated low-grade appendiceal mucinous neoplasms (LAMN II). In a selected group of LAMN II patients without established PMP, CRS/HIPEC can be performed laparoscopically (L-CRS/HIPEC); however the short-term benefits and safety of this approach have yet to be determined. This study aims to determine the short-term outcomes from a series of L-CRS/HIPEC LAMN II patients compared to those who have undergone a similar open operation (O-CRS/HIPEC) for low-volume PMP.

Methods

LAMN II patients undergoing L-CRS/HIPEC at a UK national peritoneal tumour centre were compared to O-CRS/HIPEC patients (peritoneal cancer index ≤ 7). Outcomes of interest included Clavien–Dindo complication grade, operative time, blood transfusions, high dependency unit (HDU) admission, length of hospital stay, and histopathological findings.

Results

55 L-CRS/HIPEC were compared to 29 O-CRS/HIPEC patients (2003–2017). Groups were matched for age, sex, and procedures. Median operative time was 8.8 (IQR 8.1–9.5) h for L-CRS/HIPEC versus 7.3 (IQR 6.7–8) h for O-CRS/HIPEC (Mann–Whitney test p < 0.001). Post-operative HDU admission was 56% versus 97% (OR 0.04 95% CI 0.01–0.34) and median length of stay = 6 (IQR 5–8) versus 10 (IQR 8–11) days (p < 0.001) for L- versus O-CRS/HIPEC. Despite a normal pre-operative CT scan, 13/55 (23.6%) L-CRS/HIPEC patients had acellular mucin and 2/55 (3.5%) had mucin with epithelium present in their specimens. Residual appendix tumour was identified in 2/55 patients (3.6%). Clavien–Dindo Grade 1–4 complications were similar in both groups with no mortality.

Conclusion

L-CRS/HIPEC for LAMN II takes longer; however patients have significantly reduced length of HDU and overall stay, without increased post-operative complications. A significant proportion of LAMN II patients undergoing L-CRS/HIPEC have extra-appendiceal acellular mucin with some cases demonstrating residual cellular epithelium from the LAMN II. The risk of these patients developing PMP without surgery is under current review.

Risk of Appendiceal Neoplasm in Periappendicular Abscess in Patients Treated With Interval Appendectomy vs Follow-up With Magnetic Resonance Imaging: 1-Year Outcomes of the Peri-Appendicitis Acuta Randomized Clinical Trial

Importance

The step after conservative treatment of periappendicular abscess arouses controversy, ranging from recommendations to abandon interval appendectomy based on low recurrence rates of the precipitating diagnosis to performing routine interval appendectomy owing to novel findings of increased neoplasm risk at interval appendectomy. To our knowledge, there are no randomized clinical trials with sufficient patient numbers comparing these treatments.

Objective

To compare interval appendectomy and follow-up with magnetic resonance imaging after initial successful nonoperative treatment of periappendicular abscess.

Design, Setting, and Participants

The Peri-Appendicitis Acuta randomized clinical trial was a multicenter, noninferiority trial conducted in 5 hospitals in Finland. All patients between age 18 and 60 years with periappendicular abscess diagnosed by computed tomography and successful initial nonoperative treatment from January 2013 to April 2016 were included. Data analysis occurred from April 2016 to September 2017.

Interventions

Patients were randomized either to interval appendectomy or follow-up with magnetic resonance imaging; all patients underwent colonoscopy.

Main Outcomes and Measures

The primary end point was treatment success, defined as an absence of postoperative morbidity in the appendectomy group and appendicitis recurrence in the follow-up group. Secondary predefined end points included neoplasm incidence, inflammatory bowel disease, length of hospital stay, and days of sick leave.

Results

A total of 60 patients were included (36 men [60%]; median [interquartile range] age: interval appendectomy group, 49 [18-60] years; follow-up group, 47 [22-61] years). An interim analysis in April 2016 showed a high rate of neoplasm (10 of 60 [17%]), with all neoplasms in patients older than 40 years. The trial was prematurely terminated owing to ethical concerns. Two more neoplasms were diagnosed after study termination, resulting in an overall neoplasm incidence of 20% (12 of 60). On study termination, the overall morbidity rate of interval appendectomy was 10% (3 of 30), and 10 of the patients in the follow-up group (33%) had undergone appendectomy.

Conclusions and Relevance

The neoplasm rate after periappendicular abscess in this small study population was high, especially in patients older than 40 years. If this considerable rate of neoplasms after periappendicular abscess is validated by future studies, it would argue for routine interval appendectomy in this setting.

Trial Registration

ClinicalTrials.gov identifier: NCT03013686.

Surveillance of Low-Grade Appendiceal Mucinous Neoplasms With Peritoneal Metastases After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy: Are 5 Years Enough? A Multisite Experience

BACKGROUND

Low-grade appendiceal mucinous neoplasms (LAMNs) are tumors that often present with widespread mucin in the peritoneal cavity (pseudomyxoma peritonei [PMP]). Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are effective treatment, but no published recommendations exist regarding surveillance.

METHODS

Data from prospective databases of patients who underwent CRS-HIPEC from 2001 to 2017 at two high-volume institutions were retrospectively analyzed. Patients who underwent complete CRS-HIPEC for PMP secondary to LAMN were included in the analysis. Pathologic examination confirmed the diagnosis of LAMN. Cases of mucinous adenocarcinomas and neuroendocrine tumors (goblet cell carcinoids) were excluded.

RESULTS

The study enrolled 156 patients. The median peritoneal cancer index (PCI) was 18 (interquartile range IQR1-3, 12-23), and 125 patients (80.1%) had a CC0 cytoreduction. According to American Joint Committee on Cancer (AJCC) grading, 152 patients (97.4%) presented with acellular mucin or G1 implants, 2 patients (1.3%) presented with G2 disease, and 2 patients (1.3%) presented with G3 disease. During the follow-up period (median, 45 months; IQR1-3 23-76 months), 23 patients (14.7%) experienced recurrence. All the recurrences were peritoneal and occurred within 5 years. The 1-, 3-, and 5-year disease-free survival (DFS) rates were respectively 95.5%, 83.4%, and 78.3%. Univariate Cox regression analysis showed that higher PCI scores (p < 0.001), a CC1 cytoreduction (p = 0.005), and higher preoperative levels of carcinoembryonic antigen (CEA) (p = 0.012) and CA-125 (p = 0.032) correlated with a shorter DFS. Only higher PCI scores independently predicted earlier recurrences (p < 0.001).

CONCLUSION

Most patients had recurrence within 3 years after CRS-HIPEC, and none after 5 years. High PCI was the only independently significant variable. The study findings support intensive surveillance (every 3-6 months) with tumor markers and imaging methods during the first 3 years, and annual surveillance thereafter, with follow-up assessment after 5 years yielding limited benefit.

Referral and treatment pathways for pseudomyxoma peritonei of appendiceal origin within a national treatment programme

AIM

Pseudomyxoma peritonei (PMP) is a rare neoplasm of the appendix, which if untreated disseminates throughout the abdominal cavity and generates considerable morbidity. Since 2002 in the UK, patients with PMP have been managed via two nationally commissioned centres. We evaluated referrals and treatment pathways over time at the Manchester centre.

METHOD

Data from all patients referred with suspected PMP were prospectively collected (2002-2015). Definitive treatment was cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy. Disease burden was quantified using the Peritoneal Cancer Index (PCI) (score 0-39) and complete cytoreduction (CC) defined by scores of 0/1. Novel treatment algorithms were developed for patients with low grade appendiceal mucinous neoplasm (LAMN) localized to the peri-appendiceal tissue.

RESULTS

In all, 817 patients with confirmed PMP were referred increasing from 11 in 2002 to 103 in 2015. Disease burden was high with a mean PCI of 31 in the first quartile (Q1), levelling off to 15, 15, 17 thereafter (P = 0.002). The proportion of CC0/1 increased from 67% in Q1 to 77% Q2 and 74% Q3/4. Where complete cytoreduction was achieved, 5- and 10-year overall survival was 77% and 66%. The proportion of patients referred with localized LAMN increased over time reaching 25% each year since 2010 (P_trend  < 0.0001). Two-thirds of localized LAMN now undergo laparoscopically assisted risk-reducing CRS.

CONCLUSION

The establishment of a national treatment centre was associated with an initial presentation of patients with advanced disease. The programme has demonstrated a clear trend over time towards earlier referral and adoption of minimally invasive techniques for localized disease.