Histopathological diagnosis of appendiceal neuroendocrine neoplasms: when to perform a right hemicolectomy? A systematic review and meta-analysis

Factors Affecting Survival Outcomes in Neuroendocrine Tumor of the Appendix over the Past Two Decades

BACKGROUND

Appendiceal neuroendocrine tumors (NETs) rank as the third most frequent neoplasm affecting the appendix, originating from enterochromaffin cells. This study aims to evaluate the influence of various prognostic factors on the mortality rates of patients diagnosed with NETs of the appendix.

METHODS

Conducted retrospectively, the study involved 3346 patients, utilizing data sourced from the Surveillance, Epidemiology, and End Results (SEER) database. Our analysis centered on investigating demographic characteristics, clinical features, overall mortality (OM), and cancer-specific mortality (CSM) among the cohort. Variables showing a p-value < 0.1 in the univariate Cox regression were incorporated into the multivariate Cox regression analysis. A Hazard Ratio (HR) > 1 indicated an unfavorable prognosis.

RESULTS

In the multivariate analysis, higher OM and CSM were observed in males, older age groups, tumors with distant metastasis, poorly differentiated tumors, and those who underwent chemotherapy. Non-Hispanic Black individuals showed elevated mortality rates.

CONCLUSION

Delayed diagnosis may contribute to the increased mortality in this community. Improved access to healthcare and treatment is crucial for addressing these disparities. Larger prospective studies are needed to pinpoint the underlying causes of elevated mortality in non-Hispanic Black populations, and randomized controlled trials (RCTs) are warranted to evaluate therapies for advanced-stage appendix NETs.

Appendiceal Neuroendocrine Neoplasms: an Update for 2023

PURPOSE OF REVIEW

To summarize the literature from the last 5 years on treatment of appendiceal neuroendocrine neoplasms (aNEN). Furthermore, to evaluate the prognostic significance of lymph node metastases, indications for adjuvant treatment, and challenges of the current follow-up regimen.

RECENT FINDINGS

Simple appendectomy is sufficient in tumors < 1 cm while extended surgery is indicated in tumors > 2 cm. In a multicenter study of aNENs measuring 1-2 cm, extended surgery offered no significant prognostic advantage and is now limited to incomplete tumor resection or high-grade G2 or G3 aNEN. Follow-up remains debatable, as the use of imaging and biomarkers lacks validation. While surgical procedure is well established in aNEN tumors < 1 cm and > 2 cm, the need for extended surgery in aNEN tumors 1-2 cm is questionable. Future studies should address the prognostic impact of lymph node metastases and the optimal design and duration of follow-up.

Utility of histopathological revision in the management of gastro-entero-pancreatic neuroendocrine neoplasia

BACKGROUND

Histological evaluation and grading assessment are key points in the diagnostic work-up of gastroentero-pancreatic neuroendocrine neoplasms (GEP-NENs).

AIM

To analyze the impact of histopathological revision on the clinical management of patients with GEP-NEN.

MATERIALS AND METHODS

Patients referred to our Center of Excellence between 2015 and 2021 were included in this study. Immunohistochemical slides at the time of initial diagnosis were reviewed to assess tumor morphology, diagnostic immunohistochemistry, and Ki67.

RESULTS

101 patients were evaluated, with 65 (64.4%) gastrointestinal, 25 (24.7%) pancreatic, and 11 (10.9%) occult neoplastic lesions suspected to be of GEP origin. The main changes resulting from the revision were: first Ki-67 assessment in 15.8% of patients, Ki-67 change in 59.2% of patients and grading modification in 23.5% of patients. An additional immunohistochemical evaluation was performed in 78 (77.2%) patients, leading to a confirmation of GEP origin in 10 of 11 (90.9%) of unknown primary site neoplastic lesions and an exclusion of NEN diagnosis in 2 (2%) patients. After histopathological revision, a significant modification in clinical management was proposed in 42 (41.6%) patients.

CONCLUSIONS

Histopathological revision in a referral NEN center is strongly advised in newly diagnosed GEP-NENs to properly plan prognostic stratification and therapeutic choice.

European Neuroendocrine Tumor Society (ENETS) 2023 guidance paper for appendiceal neuroendocrine tumours (aNET)

The aim of the present guidance paper is to update the previous ENETS guidelines on well differentiated appendiceal neuroendocrine tumours (NET), providing practical guidance for the diagnosis and management of appendiceal NET (aNET); poorly differentiated neoplasms are dealt with in a separate guidance paper. This paper is structured on a question-answer format in order to also address controversial issues and areas where uncertainty regarding the management and follow-up of aNET exists. All recommendations are offered on the basis of the best available evidence, along with the authors' experiences in managing these neoplasms. Each recommendation for treatment will provide a level of evidence and grade of recommendation as per the GRADE system (adapted in Infectious Disease Society of United States Public Health Service grading system).

Appendiceal neuroendocrine neoplasms and resection of the mesoappendix: a retrospective comparative study

PURPOSE

Incidental appendiceal neoplasms are identified in approximately 1% of the specimens of suspected appendicitis. The current institutional policy is to perform en bloc mesoappendix resection during routine laparoscopic appendicectomy allowing for staging, reducing the need for oncological right hemicolectomy (ORH). Herein, we review en bloc mesoappendicectomy in clinical practice and its effects on the rate of ORH.

METHODS

We reviewed all cases of appendicectomy performed at the Auckland City Hospital between 1 May 2014 and 31 May 2019. Clinical notes and histopathological reports were reviewed. All neoplasms, surgical techniques and the need for further surgery were analysed.

RESULTS

A total of 2455 appendicectomies were performed with an approximately similar number of procedures between the sexes and an overall median age of 31 years. Overall, 86% (n = 2098) of the specimens included resection of the mesoappendix, and 58 (2.4%) appendiceal neoplasms were identified. Of them, 33 (1.3%) specimens included neuroendocrine appendiceal neoplasms. Eleven (33%) patients with appendiceal neuroendocrine neoplasms were recommended ORH. One of these patients may have avoided additional surgery, whereas 3 (9.1%) patients with tumours of 10-20 mm avoided ORH because their mesoappendix was resected.

CONCLUSION

At our centre, there has been a significant change in the practice of mesoappendix resection, and we support resection of the mesoappendix during appendicectomy. The procedure is technically straightforward and safe, incurs no increases in costs or time, allows for accurate tumour staging and guides decisions regarding further surgical interventions.

An Update on Appendiceal Neuroendocrine Tumors

The mainstay of appendiceal neuroendocrine neoplasm (aNEN) treatment is surgery, based on simple appendectomy or right-sided hemicolectomy with lymphadenectomy (RHC). The majority of aNENs are adequately treated with appendectomy, but current guidelines have poor accuracy in terms of selecting patients requiring RHC, especially in aNENs 1-2 cm in size. Simple appendectomy is curative for appendiceal NETs (G1-G2) < 1 cm (if the resection status is R0), whereas RHC with lymph node dissection is recommended in tumors ≥ 2 cm in diameter, based on the high risk of nodal metastases in these cases. The clinical management of aNENs 1-2 cm in size is more controversial because lymph node or distant metastases are uncommon but possible. In our opinion, patients with tumor size > 15 mm or with grading G2 (according to WHO 2010) and/or lympho-vascular invasion should be referred for radicalization with RHC. However, decision-making in these cases should include discussion within a multidisciplinary tumor board at referral centers with the aim of offering each patient a tailored treatment, also considering that relatively young patients with long-life expectancy represent the majority of cases.

Clinical and pathologic characteristics of appendiceal neuroendocrine neoplasms diagnosed during pregnancy

INTRODUCTION

Although appendicitis occurs in approximately 1:1000 pregnancies, appendiceal neuroendocrine neoplasm (ANEN) diagnosis during pregnancy is very rare. Data on presentation, treatment and prognosis is scarce.

AIM

To describe ANEN cases diagnosed during pregnancy.

MATERIALS AND METHODS

A retrospective appraisal of 7 consecutive ANEN patients diagnosed during pregnancy from four Israeli tertiary medical centers and comparison with 17 cases described in the literature from 1965-2021.

RESULTS

Age at ANEN diagnosis was 26.4 ± 3.5 years (range 21-33). Patients were diagnosed between gestational weeks 6-40, most frequently in the third trimester (53%). The most common presenting symptom was abdominal pain. Tumor size was 14.3 ± 8.9mm (range 3-45mm). In patients from our series appendiceal base involvement was reported in 2/7; mesoappendiceal invasion in 5/7; lympho-vascular invasion in 2/7. Ki67 staining was reported in 6/7 cases and ranged from 1-10%. Pathology details were lacking in most of the previously published cases. All 7 pregnancies in our series resulted in term delivery with no complications, whereas in historical cases there were one first trimester abortion, one ectopic pregnancy, and one stillbirth. Right hemicolectomy was performed in 5/7 patients in our series and reported in 2/17 historical cases. All hemicolectomies were performed after delivery, 3-16 months after appendectomy. Local metastases were reported in two cases. Follow-up duration was 7-98 months for our patients and 3-48 months in 5 historical cases. No disease recurrence, distant metastases or mortality were noted.

CONCLUSIONS

To the best of our knowledge, this is the largest series describing the extremely rare diagnosis of ANEN during pregnancy. Although pathologic characteristics varied, pregnancy outcomes were usually favorable and long-term prognosis was excellent. This data may suggest that a conservative approach to patients with ANEN diagnosis during pregnancy can be considered.

Surgical Treatment of Neuroendocrine Tumors of the Terminal Ileum or Cecum: Ileocecectomy Versus Right Hemicolectomy

BACKGROUND

Simple ileocecectomy and right hemicolectomy are two potential operative approaches to treat patients with neuroendocrine neoplasm in the terminal ileum and/or cecum (IC-NENs). We sought to define the long-term outcome of patients undergoing ileocecectomy versus right hemicolectomy for IC-NENs, as well as characterize number of nodes evaluated and lymph node metastasis (LNM) associated with each procedure.

METHODS

Patients who underwent curative-intent resections for IC-NENs between 2000 and 2016 were identified from a multi-institutional database. The clinicopathologic characteristics, surgical procedures, and the overall (OS) and recurrence-free survival (RFS) were compared among patients who underwent formal right hemicolectomy versus ileocecectomy only.

RESULTS

Among 127 patients with IC-NENs, median size of the largest tumor size was 2.0 (IQR 1.2-2.9) cm; 35 (27.6%) patients had multiple lesions. At the time of surgery, 93 (73.2%) patients underwent a right hemicolectomy, whereas 34 (26.8%) had ileocecectomy only. Every patient had a lymph node dissection (LND) with a median number of 16 (IQR 12-22) nodes evaluated. A majority (n = 110, 86.6%) of patients had LNM with a median number of 3 (IQR 2-5) LNM. Patients who underwent hemicolectomy had more lymph nodes evaluated versus patients who had an ileocecectomy only (median, 18 vs. 14, p = 0.004). Patients who underwent formal right hemicolectomy versus ileocecectomy had a similar OS (median OS, 101.9 vs. 144.5 months, p = 0.44) and RFS (median RFS, 70.3 vs. not attained, p = 0.80), respectively.

CONCLUSIONS

Ileocecectomy had similar long-term outcomes versus right hemicolectomy in treatment of IC-NENs despite a difference in the lymph node harvest.

Management of incidentally discovered appendiceal neuroendocrine tumors after an appendicectomy

Appendiceal neuroendocrine tumors (aNETs) are an uncommon neoplasm that is relatively indolent in most cases. They are typically diagnosed in younger patients than other neuroendocrine tumors and are often an incidental finding after an appendectomy. Although there are numerous clinical practice guidelines on management of aNETs, there is continues to be a dearth of evidence on optimal treatment. Management of these tumors is stratified according to risk of locoregional and distant metastasis. However, there is a lack of consensus regarding tumors that measure 1-2 cm. In these cases, some histopathological features such as size, tumor grade, presence of lymphovascular invasion, or mesoappendix infiltration must also be considered. Computed tomography or magnetic resonance imaging scans are recommended for evaluating the presence of additional disease, except in the case of tumors smaller than 1 cm without additional risk factors. Somatostatin receptor scintigraphy or positron emission tomography with computed tomography should be considered in cases with suspected residual or distant disease. The main point of controversy is the indication for performing a completion right hemicolectomy after an initial appendectomy, based on the risk of lymph node metastases. The main factor considered is tumor size and 2 cm is the most common threshold for indicating a colectomy. Other factors such as mesoappendix infiltration, lymphovascular invasion, or tumor grade may also be considered. On the other hand, potential complications, and decreased quality of life after a hemicolectomy as well as the lack of evidence on benefits in terms of survival must be taken into consideration. In this review, we present data regarding the current indications, outcomes, and benefits of a colectomy.

Acute appendicitis–advances and controversies

Being one of the most common causes of the acute abdomen, acute appendicitis (AA) forms the bread and butter of any general surgeon’s practice. With the recent advancements in AA’s management, much controversy in diagnostic algorithms, possible differential diagnoses, and weighing the management options has been generated, with no absolute consensus in the literature. Since Alvarado described his eponymous clinical scoring system in 1986 to stratify AA risk, there has been a burgeoning of additional scores for guiding downstream management and mortality assessment. Furthermore, advancing literature on the role of antibiotics, variations in appendicectomy, and its adjuncts have expanded the surgeon’s repertoire of management options. Owing to the varied presentation, diagnostic tools, and management of AA have also been proposed in special groups such as pregnant patients, the elderly, and the immunocompromised. This article seeks to raise the critical debates about what is currently known about the above aspects of AA and explore the latest controversies in the field. Considering the ever-evolving coronavirus disease 2019 situation worldwide, we also discuss the pandemic’s repercussions on patients and how surgeons’ practices have evolved in the context of AA.

Paediatric appendiceal neuroendocrine tumours: a review of 33 cases from a single center

BACKGROUND

Appendiceal neurendocrine tumours (NETs) are rare neoplasms and diagnosis is commonly incidental following appendectomy. We aimed to review our experience with appendiceal NETs.

METHODS

Records of children with appendiceal NETs were reviewed and data concerning demographic characteristics, clinical findings, surgical procedures, histopathological findings, management and outcomes were recorded.

RESULTS

Between 1985 and 2021, 33 cases with appendiceal NETs (median age 11.8 years, range 7.8-16; male/female = 10/23) were identified. All but one patients presented with abdominal pain, six had vomiting, four had fever and they underwent appendectomies with presumed diagnosis of acute appendicitis. Abscess drainage and appendectomy was performed in a 16-year-old girl for suspected right ovarian mass, and tumour was positive in the omentum. Histopathological diagnosis was classical carcinoid tumour (NET) in all cases. Median tumour size was 0.9 cm (n = 26, range, 0.1-3.5 cm); tumours were ≤1 cm in 19 cases, 2 cm in one, 3.5 cm in another case. Tumours were located in the tip (n = 11), body (n = 6) and base of appendix (n = 1) (in others data unavailable). In 28 patients with data, tumour extended to submucosa in five, to tunica muscularis in seven, to subserosa in six, to serosa in six, to mesoappendix in three, to periappendiceal fat in one. Three cases were lost to follow-up, 31 cases were alive (median follow-up 53 months).

CONCLUSIONS

Paediatric appendiceal NETs do not behave aggressively and appendectomy alone is sufficient for tumours ≤2 cm regardless of local invasion. The need for further extensive surgery in tumours >2 cm also remains controversial.

Lessons learned about appendiceal neuroendocrine neoplasms from data analysis of the Belgian Cancer Registry 2010-2015

BACKGROUND AND STUDY AIMS

Appendiceal neuroendocrine neo-plasms (aNENs) are a diverse group of malignant neoplasms of varying biological behavior for which information about manage-ment and outcome is sparse, with the majority of available studies being retrospective, including only a limited number of patients, and therefore not necessarily reflecting the reality in the community. In the present study clinical, epidemiological and pathological data of appendiceal neuroendocrine neoplasms in Belgium is provided and compared with current literature.

METHODS

A population-based study was conducted by linking data of the Belgian Cancer Registry with medical procedures in the Belgian Health Insurance database for patients diagnosed with aNEN between 2010 and 2015.

RESULTS

We found an aNEN incidence of 0.97/100.000 person years in Belgium. Neuroendocrine carcinoma of the appendix are rare. Most appendiceal neuroendocrine tumors (aNETs) are small G1 tumors. Positive lymph nodes are often found in tumors larger than 2cm, especially aNET G2.

CONCLUSION

A rapid uptake of changing classifications was seen in the community. However, systematic reporting of risk factors for small aNEN can still be improved and should be stimulated. In 9% of cases, reclassifications had to be made, pointing out that in a retrospective analysis, original pathological reports should be checked for specific parameters, before reliable conclusions can be drawn.

Update on gastroenteropancreatic neuroendocrine tumors

The incidence gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) has dramatically risen over the last three decades, probably due to the increased detection of asymptomatic lesions. The diagnostic work-up for patients with suspected GEP-NENs is based on conventional imaging, endoscopy, pathology, and functional imaging, including ⁶⁸Gallium-DOTATATE PET and ¹⁸F-FDG PET. The choice of the best treatment strategy should be based on the evaluation of tumor-related features and patient's characteristics. A conservative management, consisting of active surveillance or endoscopic resection, has been advocated for patients with small, incidentally discovered, nonfunctioning tumors without features of aggressiveness. On the other hand, surgery with lymphadenectomy, also with a minimally invasive approach, represents the gold standard for the curative treatment of localized disease. Moreover, surgical resection plays an important role also in the context of a multimodal treatment strategy for patients with advanced GEP-NENs. Finally, a wide range of medical therapies, comprising somatostatin analogues, peptide receptor radionuclide therapy, target therapies and several chemotherapy regimens, can be offered to patients with advanced GEP-NENs not amenable of surgical resection, according to the biological and molecular features of their disease.

The effect of prophylactic surgery in survival and HRQoL in appendiceal NEN

BACKGROUND/AIMS

Long-term outcomes are understudied in patients with well-differentiated appendiceal neuroendocrine neoplasms (WD-ANENs). We aimed to evaluate the validity of currently applied criteria for completion prophylactic right hemicolectomy (pRHC) and determine its association with patient outcomes, including health-related quality of life (HRQoL).

METHODS

Eligible patients from five European referral centers were divided between those who underwent appendectomy alone and those who underwent completion pRHC. HRQoL EORTC-QLC-C30 questionnaires and cross-sectional imaging data were prospectively collected. Age- and sex-matched healthy controls were recruited for HRQoL analysis' validation.

RESULTS

We included 166 patients (119 women [71.2%]: mean age at baseline: 31 ± 16 years). Mean follow-up was 50.9 ± 54 months. Most patients (152 [92%]) had tumors ≤20 mm in size. Fifty-eight patients (34.9%) underwent pRHC that in final analysis was regarded as an overtreatment in 38/58 (65.5%). In multivariable analysis, tumor size >20 mm was the only independent predictor for lymph node (LN) involvement (p = 0.002). No mortality was reported, whereas 2-, 5- and 10-year recurrence-free survival in patients subjected to postoperative cross-sectional imaging (n = 136) was 98.5%, 97.8%, and 97.8%, respectively. Global HRQoL was not significantly impaired in patients with WD-ANEN compared with age- and sex-matched healthy individuals (median scores 0.83[0.08-1] vs 0.83[0.4-1], respectively; p = 0.929). Among patients with WD-ANEN impaired social functioning (p = 0.016), diarrhea (p = 0.003) and financial difficulties (0.024) were more frequently reported in the pRHC group.

CONCLUSIONS

WD-ANEN is a low-malignant neoplasm with unconfirmed associated mortality, low recurrence rate, and overall preserved HRQoL. pRHC comes at a price of excessive surgery, functional HRQoL issues, and diarrhea. The value per se of a prophylactic surgical approach to patients with WD-ANENs <20 mm is challenged.

Temporal trends in incidence, evaluation and management of neuroendocrine neoplasms of the appendix: 14 years' experience

BACKGROUND

Information regarding temporal trends in appendiceal neuroendocrine neoplasms (ANEN) is limited. This retrospective study evaluated temporal trends in ANEN incidence and management over a 14-year period.

METHODS

Appendectomy pathology reports from a single tertiary center were reviewed.

RESULTS

During 2005-2018, 8327 appendectomies were performed and 57 ANENs were diagnosed (average age 31.7 ± 17 years; 70.2% women; 17.5% Arab ethnicity; and 22.8% < 18 years of age). The cohort was divided according to year of diagnosis (Period A 2005-2011; Period B 2012-2018). No differences were found in ANEN incidence (0.75% and 0.62%, respectively, p = 0.104), epidemiologic or pathologic characteristics between periods. In period B, pathology reports were more comprehensive and use of specific imaging and biochemical studies was more prevalent. Hemicolectomy rates and results were similar (8 in Period A, 7 in Period B, p = 0.925). All patients remained alive for the duration of follow-up.

CONCLUSIONS

No temporal changes in epidemiological, clinical or pathological features of ANENs were noted. Although clinico-pathological evaluation was more detailed after 2011, there was no change in rates of hemicolectomy or disease prognosis.

The risk of lymph node metastases and their impact on survival in patients with appendiceal neuroendocrine neoplasms: a systematic review and meta-analysis of adult and paediatric patients

BACKGROUND

There are no clear histopathological parameters determining the risk of lymph node (LN) metastases and appropriateness of completion prophylactic right hemicolectomy (RHC) in patients with appendiceal neuroendocrine neoplasms (ANENs).

MATERIALS AND METHODS

The PubMed, Cochrane Library, Embase, Web of Science and SCOPUS databases were searched up to November 2018. Quality/risk of bias was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

A total of 526 articles were screened. In 11 adult and 3 paediatric studies, 602 and 77 unique patients, respectively, with ANEN and undergoing RHC, were included. The rate of LN metastases for a cutoff size >10 mm was 48.6% (vs 12.1% for lesions <10 mm) among adult patients, with an odds ratio (OR) of 4.8 (95% CI, 1.5-15.8). For 20 mm size cutoff, these figures were 61% (vs 28.2% for lesions <20 mm) with an OR of 3.2 (95% CI, 1.3-7.8). Vascular-, lymph vessel- and perineural invasions were identified as predictive factors for LN metastases in adult patients. In paediatric patients, there were no strong morphological predictors for LN metastases. The 10-year disease-specific survival (DSS) for adult patients without LN metastases was 99.2% vs 95.6% in patients with LN (OR: 0.2; 95% CI, 0.02-2.4). The complication rate of prophylactic RHC was 11.4%.

CONCLUSIONS

This meta-analysis demonstrates that tumour size >20 mm as well as >10 mm and/or vascular-, lymph vessel- and perineural invasions are associated with increased risk for LN metastases in adult patients with ANEN. The prognostic value of LN positivity remains to be determined in further studies with long-term follow-up.