This review article explores the evolving landscape of Molecular Radiotherapy (MRT), emphasizing Peptide Receptor Radionuclide Therapy (PRRT) for neuroendocrine tumours (NETs). The primary focus is on the transition from β-emitting radiopharmaceuticals to α-emitting agents in PRRT, offering a critical analysis of the radiobiological basis, clinical applications, and ongoing developments in Targeted Alpha Therapy (TAT). Through an extensive literature review, the article delves into the mechanisms and effectiveness of PRRT in targeting somatostatin subtype 2 receptors, highlighting both its successes and limitations. The discussion extends to the emerging paradigm of TAT, underlining its higher potency and specificity with α-particle emissions, which promise enhanced therapeutic efficacy and reduced toxicity. The review critically evaluates preclinical and clinical data, emphasizing the need for standardised dosimetry and a deeper understanding of the dose-response relationship in TAT. The review concludes by underscoring the significant potential of TAT in treating SSTR2-overexpressing cancers, especially in patients refractory to β-PRRT, while also acknowledging the current challenges and the necessity for further research to optimize treatment protocols.

Small intestinal neuroendocrine tumours (SI-NETs) are the most common small intestinal tumours. A particularly challenging subset of these tumours is those that involve the superior mesenteric artery or vein for which the role and feasibility of surgery are often questioned. This systematic review aimed to identify and evaluate the management strategies used for these complex SI-NETs. The identified studies showed positive outcomes with surgery and multimodality therapy.

Although anti-vascular endothelial growth factor (VEGF) receptor tyrosine kinase inhibitors (RTKIs) have been tested in patients with neuroendocrine tumours (NETs) over the last two decades, no study to date has benchmarked efficacy and toxicity of these drugs in this patient population.
All phase II and phase III studies of anti-VEGF RTKIs in patients with NETs, published between January 1, 2000 andJuly 31, 2021, across major trial databases, were searched in August 2021 for relevant studies. The primary objectives of the meta-analysis were to compare objective response rate (ORR) and progression-free survival (PFS) between patients with pancreatic NETs (pNETs) and extra-pancreatic NETs (epNETs), and the incidence rate ratio (IRR) of adverse events between patients receiving anti-VEGF RTKIs and control.
1611 patients were available for the meta-analysis; 1194 received anti-VEGF RTKIs. ORR in pNETs was 18% (95% confidence interval (CI) 13-25%), while ORR in epNETs was 8% (95% CI 5-12%); test for differences between pNETs and epNETs (x12 = 8.38, p < .01). Median PFS in pNETs was 13.9 months (95% CI 11.43-16.38 months), while median PFS in epNETs was 12.71 months (95% CI 9.37-16.05 months); test for differences between pNETs and epNETs (x12 = .35, p = .55). With regards to common grade 3/4 adverse events , patients who received anti-VEGF RTKIs were more likely to experience hypertension (IRR 3.04, 95% CI 1.63-5.65) and proteinuria (IRR 5.79, 95% CI 1.09-30.74) in comparison to those who received control.
Anti-VEGF RTKIs demonstrate anti-tumour effect in both pNETs and epNETs, supporting their development in both populations. These agents also appear to be safe in patients with NETs.

The aim of this study was to evaluate the efficacy and safety of 177 Lu-DOTATATE therapy in advanced metastatic disease. A retrospective analysis of 395 patients (180 female, 215 males, mean age 62) with progressive metastatic neuroendocrine tumours (NETs) who were treated with 177 Lu-DOTATATE was performed. Overall, 115 patients had less than four cycles and 280 completed four cycles of treatment. Progression-free survival (PFS) and overall survival (OS) was performed using Kaplan-Meier analysis. Analysis of survival predictors was performed using Cox regression model. Toxicity was defined using the Common Terminology Criteria for Adverse Events version 5 (CTCAE 5.0). The percentage of patients with liver and skeletal metastases were 91 and 57%, respectively. Median PFS and OS were calculated at 33 months (95% CI: 29-37 months) and 46 months (95% CI: 48-56 months), respectively. End of treatment response assessment was performed using cross sectional imaging demonstrated partial response in 22%, stable disease in 64% and progressive disease in 14% of patients. Overall, grade 3 and 4 bone marrow toxicity was seen in 8%. One patient (0.3%) developed irreversible grade 4 nephrotoxicity. Myelodysplastic disease was recorded in one patient (0.3%). Univariate analysis of PFS predictors showed that body mass index (BMI), baseline chromogranin A (CgA) >400 ng/l, baseline alkaline phosphatase (ALP) >130 mg/dl, liver tumour volume and overall tumour burden were significant. On multivariate analysis only Ki67, high CgA and low BMI retained significance. 177 Lu-DOTATATE is an effective treatment in advanced NETs with generally high-volume metastases. It is well-tolerated. Ki-67, CgA and BMI appear to be predictors for PFS.

Appendiceal neurendocrine tumours (NETs) are rare neoplasms and diagnosis is commonly incidental following appendectomy. We aimed to review our experience with appendiceal NETs.
Records of children with appendiceal NETs were reviewed and data concerning demographic characteristics, clinical findings, surgical procedures, histopathological findings, management and outcomes were recorded.
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).
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.

OBJECTIVE: Pituitary metastases (PM) are uncommon findings and are mainly derived from breast and lung cancers. No extensive review of PM from neuroendocrine neoplasms (NENs) is on record. Here we describe a clinical case of PM from pancreatic NEN and review the clinical features of PM from NENs reported in the literature.
METHODS: A case of PM from a pancreatic NEN followed at our institution is described. We also reviewed the 43 cases of PM from NENs reported in the literature.
RESULTS: A 59-year old female patient, previously submitted to duodeno-cephalo-pancreasectomy for a well-differentiated pancreatic NEN, with known hepatic metastases, underwent a 68 Ga-DOTATOC PET/CT that revealed an uptake in the pituitary gland. A subsequent MRI displayed a pituitary lesion, with suprasellar extension. After a hormonal and genetic diagnostic workup that excluded the diagnosis of MEN 1, the worsening of headache and visual impairment and the growth of the lesion lead to its surgical removal. A pituitary localization of the pancreatic NEN was identified. Regarding the published cases of PM from NENs, the most common tumour type was small cell lung cancer (SCLC), accounting for nearly half of the cases, followed by bronchial and pancreatic well differentiated NENs. The most frequent symptom was a variable degree of visual impairment, while headache was reported in half of the cases. Partial or total anterior hypopituitarism was present in approximately three quarters of the cases, while diabetes insipidus was less common. The most frequent treatment for PM was surgical resection, followed by radiotherapy and chemotherapy. The clinical outcome was in line with previous reports of PM from solid tumours, with a median survival of 14 months. Surgery of PM was associated with prolonged survival.
CONCLUSIONS: PM from NENs have clinical features similar to metastases derived from other solid tumours, albeit the involvement of the anterior pituitary seems more frequent; a thorough pituitary hormonal evaluation is mandatory, after focused radiological studies, particularly if a surgical approach is considered. The optimal management of PM remains disputed and seems mainly driven by the aggressiveness of the primary tumour and the presence of symptoms. In well-differentiated NENs, particularly in the case of symptomatic PM, surgical removal may be a reasonable approach.

Treatment of hepatic metastases from neuroendocrine tumours improves survival and symptom relief. Hepatic arterial embolotherapy techniques include transarterial chemoembolization (tace) and bland embolization (tae). The relative efficacy of the techniques is controversial. The purpose of the present study was to use a meta-analysis and systematic review to compare tace with tae in the treatment of hepatic metastases.
A literature search identified studies comparing tace and tae for treatment of hepatic metastases. Outcomes of interest included overall survival (os), progression-free survival (pfs), radiographic response, complications, and symptom control. The hazard ratios (hrs) and odds ratios (ors) were estimated and pooled.
Eight studies and 504 patients were included. No statistically significant differences between tace and tae were observed for os at 1, 2, and 5 years or for hrs [1-year or: 0.72; 95% confidence interval (ci): 0.27 to 1.94; p < 0.52; 2-year or: 0.69; 95% ci: 0.43 to 1.11; p < 0.12; 5-year or: 0.91; 95% ci: 0.37 to 2.24; p < 0.85; hr: 0.96; 95% ci: 0.73 to 1.24; p < 0.74]. No statistically significant differences between tace and tae were observed for pfs at 1, 2, and 5 years or for hrs (1-year or: 0.71; 95% ci: 0.38 to 1.55; p < 0.30; 2-year or: 0.83; 95% ci: 0.33 to 2.06; p < 0.69; 5-year or: 0. 91; 95% ci: 0.37 to 2.24; p < 0.85; hr: 0.99-1.74; 95% ci: 0.74 to 1.73; p < 0.97). Both techniques are safe and effective for symptom control.
No statistically significant differences between tace and tae were observed for os and pfs.

UNASSIGNED: Primary neuroendocrine neoplasms (NENs) in the breast are very rare. Until 2011, the prevalence was 0.1% of all breast lesions and 1% of all NENs, whereas metastatic breast NENs represent 1%-2% of all breast tumours. However, it seems that over the last 5 years the diagnostic frequency of breast NENs has increased, probably for more alert specialists and advanced diagnostic tools, leading to a prevalence of 2%-5% of diagnosed breast cancers, mostly in the elderly population. Breast metastases from extramammary malignancies are uncommon and bilateral ones are even more uncommon, with few reported in the literature. We describe four clinical settings of breast metastases from different NENs and the multidisciplinary approach for diagnosis and treatment.
UNASSIGNED: Four patients were found to have NEN primaries metastasised to the breast. A literature review was conducted to identify similar cases and characterise breast metastases from neuroendocrinal tumors (NETs).
UNASSIGNED: Two patients presented with bilateral breast metastases (one with well-differentiated panNET and another with atypical lung carcinoid) and two had unilateral (one with moderately differentiated lung NET and one with atypical lung carcinoid). There are about 13 cases of NEN breast metastases reported in the English literature. The ileum is the most common primary site, followed by the appendix, duodenum, pancreas and lung.
UNASSIGNED: Breast lesions from extramammary primary often pose a diagnostic challenge, since a breast nodule can be the first and often the only presentation of the disease. However, differentiating between primary and secondary NEN breast lesions is essential, owing to different clinical management and prognosis.

BACKGROUND: Approximately 20% of patients with neuroendocrine tumours (NETs) develop carcinoid syndrome (CS), characterised by flushing and diarrhoea. Somatostatin analogues or telotristat can be used to control symptoms of CS through inhibition of serotonin secretion. Although CS is often the cause of diarrhoea among patients with gastroenteropancreatic NETs (GEP-NETs), other causes to consider include pancreatic enzyme insufficiency (PEI), bile acid malabsorption and small intestinal bacterial overgrowth. If other causes of diarrhoea unrelated to serotonin secretion are mistaken for CS diarrhoea, these treatments may be ineffective against the diarrhoea, risking detrimental effects to patient quality of life.
OBJECTIVE: To identify and synthesise qualitative and quantitative evidence relating to the differential diagnosis of diarrhoea in patients with GEP-NETs.
METHODS: Electronic databases (MEDLINE, Embase and the Cochrane Library) were searched from inception to September 12, 2018 using terms for NETs and diarrhoea. Congresses, systematic literature review bibliographies and included articles were also hand-searched. Any study designs and publication types were eligible for inclusion if relevant data on a cause(s) of diarrhoea in patients with GEP-NETs were reported. Studies were screened by two independent reviewers at abstract and full-text stages. Framework synthesis was adapted to synthesise quantitative and qualitative data. The definition of qualitative data was expanded to include all textual data in any section of relevant publications.
RESULTS: Forty-seven publications (44 studies) were included, comprising a variety of publication types, including observational studies, reviews, guidelines, case reports, interventional studies, and opinion pieces. Most reported on PEI on/after treatment with somatostatin analogs; 9.5%-84% of patients with GEP-NETs had experienced steatorrhoea or confirmed PEI. Where reported, 14.3%-50.7% of patients received pancreatic enzyme replacement therapy. Other causes of diarrhoea reported in patients with GEP-NETs included bile acid malabsorption (80%), small intestinal bacterial overgrowth (23.6%-62%), colitis (20%) and infection (7.1%). Diagnostic approaches included faecal elastase, breath tests, tauroselcholic (selenium-75) acid (SeHCAT) scan and stool culture, although evidence on the effectiveness or diagnostic accuracy of these approaches was limited. Assessment of patient history or diarrhoea characteristics was also reported as initial approaches for investigation. From the identified evidence, if diarrhoea is assumed to be CS diarrhoea, consequences include uncontrolled diarrhoea, malnutrition, and perceived ineffectiveness of CS treatment. Approaches for facilitating differential diagnosis of diarrhoea include improving patient and clinician awareness of non-CS causes and involvement of a multidisciplinary clinical team, including gastroenterologists.
CONCLUSIONS: Diarrhoea in GEP-NETs can be multifactorial with misdiagnosis leading to delayed patient recovery and inefficient resource use. This systematic literature review highlights gaps for further research on prevalence of non-CS diarrhoea and suitability of diagnostic approaches, to determine an effective algorithm for differential diagnosis of GEP-NET diarrhoea.

Background: Several phase-II trials have been designed to evaluate tyrosine kinase inhibitors (TKIs), in particular, pazopanib in neuroendocrine neoplasia (NEN), but its efficacy has not yet been demonstrated in a randomised-controlled Phase III trial. A systematic review of the published clinical trials of metastatic NEN patients could reduce the possible bias of single phase II studies. The present systematic review focuses on the efficacy and safety of pazopanib in patients with metastatic and locally advanced NEN. Methods: A systematic search in the major databases Medline/PubMed, Cochrane and Embase and in supplementary material from important international Meetings was performed to identify publications on pazopanib for the treatment of neuroendocrine neoplasia. English language was defined as a restriction. Four authors of the present review independently performed the study selection, assessed the risk of bias and extracted study data. Four published clinical trials and 2 abstracts were identified. One trial was excluded because the topic was Von-Hippel Landau disease and one abstract was eliminated because of the lack of information on meeting proceedings. Results: In all of the trials pazopanib was orally administered at a dose of 800 mg daily continuously with a 28-day cycle. The intention-to-treat population for efficacy was composed of 230 patients with a median age of 62 years. The partial response rate was 10.7% (95% confidence interval 2.6-20.5). The rate for stable disease was 79.6% (range: 61.7-92.1%) with a disease control rate (DCR) of 90.3%. Progressive disease was reported in 9.7% (range 5.2-17.6) of patients. No complete responses were observed. Median progression-free survival was 11.6 months (95% CI: 9.2-13.9). Overall survival from all the trials was 24.6 (95% CI: 18.7-40.8) months. Severe adverse events (grade III-IV) included hypertension 31%, 16% increase in AST/ALT, diarrhoea 10% and fatigue 10%. Conclusions: Pazopanib monotherapy achieved a DCR of 90.3% in patients with locally advanced and/or metastatic neuroendocrine neoplasia, with an overall response rate comparable to other TKIs and mTOR inhibitors and a safety profile similar to that of drugs of the same class.