Neuroendocrine Tumors Patients Research Articles

Models using comprehensive, lesion-level, longitudinal [68Ga]Ga-DOTA-TATE PET-derived features lead to superior outcome prediction in neuroendocrine tumor patients treated with [177Lu]Lu-DOTA-TATE.

Somatostatin receptor (SSTR) imaging features are predictive of treatment outcome for neuroendocrine tumor (NET) patients receiving peptide receptor radionuclide therapy (PRRT). However, comprehensive (all metastatic lesions), longitudinal (temporal variation), and lesion-level measured features have never been explored. Such features allow for capturing the heterogeneity in disease response to treatment. Furthermore, models combining these features are lacking. In this work we evaluated the predictive power of comprehensive, longitudinal, lesion-level 68GA-SSTR-PET features combined with a multivariate linear regression (MLR) model. This retrospective study enrolled NET patients treated with [177Lu]Lu-DOTA-TATE and imaged with [68Ga]Ga-DOTA-TATE at baseline and post-therapy. All lesions were segmented, anatomically labeled, and longitudinally matched. Lesion-level uptake and variation in uptake were measured. Patient-level features were engineered and selected for modeling of progression-free survival (PFS). The model was validated via concordance index, patient classification (ROC analysis), and survival analysis (Kaplan-Meier and Cox proportional hazards). The MLR was benchmarked against single feature predictions. Thirty-six NET patients were enrolled and stratified into poor and good responders (PFS ≥ 25 months). Four patient-level features were selected, the MLR concordance index was 0.826, and the AUC was 0.88 (0.85 specificity, 0.81 sensitivity). Survival analysis led to significant patient stratification (p<.001) and hazard ratio (3⨯10-5). Lastly, in a benchmark study, the MLR modeling approach outperformed all the single feature predictors. Comprehensive, lesion-level, longitudinal 68GA-SSTR-PET analysis, combined with MLR modeling, leads to excellent predictions of PRRT outcome in NET patients, outperforming non-comprehensive, patient-level, and single time-point feature predictions. Neuroendocrine tumor, peptide receptor radionuclide therapy, Somatostatin Receptor Imaging, Outcome Prediction, Treatment Response Assessment.

Gastrointestinal side effects of somatostatin analogs in neuroendocrine tumors: a focused review.

Neuroendocrine tumors (NETs) are a group of well-differentiated heterogeneous neoplasms characterized by slow progression and distinct clinical and biological behavior. In the majority of patients with NET, first-line treatment is represented by somatostatin analogs (SSAs) that, despite being drugs with high tolerability (even at high doses) and providing to carcinoid symptoms control and anti-proliferative effects, may present some side effects, with potential impact on quality of life and nutritional status. The most frequent side effects are represented by gastrointestinal events in particular alterations in bowel habits (diarrhea and constipation), abdominal pain, exocrine pancreatic insufficiency, and cholelithiasis. Considering the relative rarity of NETs, literature about frequency and standard clinical management of adverse events SSA-related is still lacking and heterogeneous. The aim of this review is to arm gastroenterologists and other physicians treating NET patients with essential knowledge on the side effects of SSAs. By identifying and managing these adverse events early, healthcare professionals can offer optimal care, avert foreseeable complications, and ensure the best outcomes for patients. Without such early recognition, there is a risk of diminishing the patient's quality of life and their ability to sustain treatment over time.

Safety and Efficacy of 177Lu-DOTATATE in Children and Young Adult Population: A Single-Center Experience.

This single-center retrospective study explores the safety and efficacy of 177Lu-DOTATATE in children and young adult population with metastatic/inoperable neuroendocrine tumors (NETs). This study is a retrospective analysis of all children and young adult patients (≤29 years) with advanced inoperable/metastatic epithelial or nonepithelial NETs who were administered a median of 4 cycles of 177Lu-DOTATATE therapy and low-dose oral capecitabine as a radiosensitizer every 8-12 weeks, except 2 patients who received CAPTEM chemotherapy. The radiological response was assessed using RECIST 1.1 on interim and end-of-treatment 68Ga-DOTANOC PET/CT. The primary endpoint was objective response rate, whereas disease control rate, toxicity profile, progression-free survival, and overall survival were secondary endpoints. Nineteen biopsy-proven NET patients (median age, 22 ± 10 years) with 8 of them adolescents (10-18 years) and the remaining young adults (19-29 years) were included. Fourteen patients had gastroenteropancreatic neuroendocrine tumor (pancreas being most common primary site), whereas the rest had non-gastroenteropancreatic neuroendocrine tumor. A total of 65 cycles of 177Lu-DOTATATE (range, 1-6 cycles) were administered with a median cumulative activity of 600 mCi (range, 100-1000 mCi). The objective response rate and disease control rate were 41% and 94%, respectively. Grade 1 and 2 adverse events were observed in 14 (74%) and 5 (26%) of 19 patients, respectively. In a total of 8 events (42%), 4 events each of disease progression and death occurred during a median follow-up of 80.1 months with an estimated 5-year progression-free survival and overall survival of 54% (95% confidence interval, 30-78) and 63% (95% confidence interval, 39-87), respectively. 177Lu-DOTATATE appears safe and effective in children and young adults with metastatic/inoperable NETs. Large prospective trials are required to validate these results.

Management of carcinoid heart disease in neuroendocrine tumor patients: a retrospective study

Management of carcinoid heart disease in neuroendocrine tumor patients: a retrospective study

Heterogeneous Uptake of 68 Ga-DOTATATE and 18 F-FDG in Initial Diagnosed Neuroendocrine Tumors Patients : Which Patients Are Suitable for Dual-Tracer PET Imaging?

This study was designed to assess the uptake heterogeneity in neuroendocrine tumor (NET) patients at initial diagnosis with dual-tracer PET imaging and the staging changes and prognostic value it brings to explore the indication of the use of dual-tracer PET. Fifty-one newly diagnosed patients with pathologically confirmed NET who underwent 18 F-FDG and 68 Ga-DOTATATE PET imaging between January 2020 and September 2022 were enrolled. Dual-tracer uptake patterns were classified into 3 groups: A. 68 Ga-DOTATATE positive and 18 F-FDG negative, B. 68 Ga-DOTATATE positive and 18 F-FDG positive, and C. 68 Ga-DOTATATE negative and 18 F-FDG positive. Descriptive statistics were used to evaluate the heterogeneity of dual-tracer uptake patterns among different grading (G) groups, between primary and metastatic lesions, and staging changes. Moreover, dual-tracer uptake patterns, grade, age, sex, and stage were compared with progression-free survival (PFS) by Cox regression. In the different G groups, none of the patients with dual-tracer uptake pattern A had grade 3 histology, but 57% of patients with grade 1 disease had FDG avidity (25% of them resulting in dual-tracer uptake pattern C). Patients with no metastasis were well differentiated, but one of them presented with dual-tracer uptake pattern C. Different uptake patterns were also observed between primary and metastatic lesions, particularly 44% of patients with dual-tracer uptake pattern A of primary with FDG avidity of metastases. Moreover, 9 (17.6%) had new lesions detected by additional 18 F-FDG PET imaging, and 3 of them (5.9%) had clinical stage changed accordingly. The Cox regression test showed that the dual-tracer uptake patterns were significantly correlated with PFS by univariate and multivariate analyses ( P = 0.026 and 0.039, respectively), whereas the grade and stage did not correlate with survival (all P >0.05). The current study has proven the uptake heterogeneity of the NET at initial diagnosis and demonstrated the staging and prognostic value of dual-tracer PET imaging. Our preliminary results have confirmed the importance of dual-tracer imaging modalities and concluded that dual-tracer PET imaging could be considered as prognostic tool for all patients with an initial diagnosis of NET.

Neuropilin 2 and soluble neuropilin 2 in neuroendocrine neoplasms.

Neuropilin 2 (NRP2), a transmembrane non-tyrosine kinase receptor, has been described as a potential critical player in the tumourigenesis of several solid cancers and particularly in neuroendocrine neoplasms (NENs). A soluble form of NRP2 (sNRP2) has been previously described and corresponds to a truncated splice isoform. Its prognostic value has never been studied in NEN. NRP2 expression was studied by immunochemistry on tissue microarrays (n = 437) and on circulating tumour cells (CTCs, n = 5 patients with neuroendocrine carcinoma, NEC). We described the levels of sNRP2 in 229 patients with NEN using the ELISA method to identify the factors associated with sNRP2 levels and to evaluate its prognostic role; 90 blood donors represented the healthy control group. NRP2 was found in 97% of neuroendocrine tumours (396/410) and in 74% of NEC (20/27). NRP2 was also expressed in CTC of all the studied patients. The receiver operating characteristic (ROC) analysis showed that sNRP2 had a weak capacity to discriminate between NEN patients and healthy controls (area under curve (AUC) = 0.601, P = 0.053). Abnormal sNRP2 levels were associated with inflammatory syndrome, bone and peritoneal metastases, and abnormal chromogranin A levels. Patients with high sNRP2 levels (sNRP2Q3-Q4) had significantly poorer overall survival in multivariate analysis (HR 0.16, 95% CI (0.04-0.67), P = 0.015). In conclusion, the present study found that sNRP2 and NRP2 could represent a new prognostic biomarker and a therapeutic target, respectively, particularly in aggressive NEN.

An automated methodology for whole-body, multimodality tracking of individual cancer lesions.

Objective. Manual analysis of individual cancer lesions to assess disease response is clinically impractical and requires automated lesion tracking methodologies. However, no methodology has been developed for whole-body individual lesion tracking, across an arbitrary number of scans, and acquired with various imaging modalities.Approach. This study introduces a lesion tracking methodology and benchmarked it using 2368Ga-DOTATATE PET/CT and PET/MR images of eight neuroendocrine tumor patients. The methodology consists of six steps: (1) alignment of multiple scans via image registration, (2) body-part labeling, (3) automatic lesion-wise dilation, (4) clustering of lesions based on local lesion shape metrics, (5) assignment of lesion tracks, and (6) output of a lesion graph. Registration performance was evaluated via landmark distance, lesion matching accuracy was evaluated between each image pair, and lesion tracking accuracy was evaluated via identical track ratio. Sensitivity studies were performed to evaluate the impact of lesion dilation (fixed versus automatic dilation), anatomic location, image modalities (inter- versus intra-modality), registration mode (direct versus indirect registration), and track size (number of time-points and lesions) on lesion matching and tracking performance.Main results. Manual contouring yielded 956 lesions, 1570 lesion-matching decisions, and 493 lesion tracks. The median residual registration error was 2.5 mm. The automatic lesion dilation led to 0.90 overall lesion matching accuracy, and an 88% identical track ratio. The methodology is robust regarding anatomic locations, image modalities, and registration modes. The number of scans had a moderate negative impact on the identical track ratio (94% for 2 scans, 91% for 3 scans, and 81% for 4 scans). The number of lesions substantially impacted the identical track ratio (93% for 2 nodes versus 54% for ≥5 nodes).Significance. The developed methodology resulted in high lesion-matching accuracy and enables automated lesion tracking in PET/CT and PET/MR.

Assessing the effectiveness and safety of surufatinib versus everolimus or sunitinib in advanced neuroendocrine neoplasms: insights from a real-world, retrospective cohort study using propensity score and inverse probability treatment weighting analysis.

While surufatinib, sunitinib, and everolimus have shown efficacy for advanced neuroendocrine neoplasms (NENs) in randomized controlled trials (RCTs), direct comparisons in a real-world setting remain unexplored. This gap highlights the clinical need to understand their comparative effectiveness and safety within the diverse Chinese population. Addressing this, our study provides insights into the real-world performance of these therapies, aiming to inform treatment selection and improve patient outcomes. A retrospective, observational study was conducted at Fudan University Shanghai Cancer Center, including patients with advanced NENs treated with surufatinib, sunitinib, or everolimus between July 2020 and April 2023. Eligibility criteria focused on histologically confirmed, locally advanced, unresectable, or metastatic NENs, with patients having received at least one month of targeted therapy. We employed inverse probability weighting (IPW) with the propensity score (PS) matching to adjust for the bias of baseline characteristics. The assessment of covariates included age, sex, performance status, primary tumor site, functional status, genetic mutations, tumor differentiation, Ki67 index, tumor grade, metastasis site, and previous therapies. The primary outcome was progression-free survival (PFS), and secondary outcomes included objective response rate (ORR), disease control rate (DCR), and adverse events (AEs). The study enrolled 123, 56, and 68 locally advanced or metastatic NEN patients treated with surufatinib, sunitinib, and everolimus, respectively. Before adjusting for confounding factors, surufatinib was used less frequently as a first-line treatment compared to sunitinib and everolimus in pancreatic NENs (pNENs) (11.1% vs. 22.1%, P=0.057). Significant differences were noted in prior treatments and tumor characteristics between surufatinib and everolimus groups in extrapancreatic NENs (epNENs) (P<0.05). Post-IPW, these disparities were resolved (P>0.05). Surufatinib demonstrated superior median PFS (mPFS) in both pancreatic [8.30 vs. 6.33 months, hazard ratio (HR) 0.592, P<0.001] and epNENs (8.73 vs. 3.70 months, HR 0.608, P<0.001) compared to everolimus or sunitinib. Notably, male gender (HR 1.75, P=0.001), functional status (HR 2.09, P=0.01), Ki67 index >20% (HR 12.7, P=0.004), previous somatostatin analogue (SSA) treatment (HR 1.73, P=0.001), germline mutation (HR 5.62, P<0.001), poor differentiation (HR 7.45, P<0.001), liver metastasis (HR 1.72, P=0.001) and multiple treatment lines (HR 1.62 for 2nd line, P=0.04; HR 1.88 for ≥3rd line, P=0.01) were identified as negative prognostic factors for PFS. Conversely, dose adjustment (HR 0.63, P=0.009) and treatment with surufatinib (HR 0.58 for pNEN, P<0.001; HR 0.62 for epNEN, P=0.002) were correlated with longer PFS. In a real-world Chinese cohort, surufatinib significantly outperformed sunitinib and everolimus in prolonging PFS among advanced NEN patients, with identifiable clinical features impacting survival, and conclusions regarding superiority should be interpreted with caution due to the retrospective design. Our findings underscore the need for prospective studies to further validate these results and explore additional predictive biomarkers for personalized treatment strategies.

Abstract 3624: A low-cost kit for gentle, effective and timely extracellular vesicle (GET EVs) isolation: Accelerating development of RNA-based liquid biopsies for neuroendocrine neoplasms

Abstract Extracellular vesicles (EVs) are cell fragments released by all cells, making them promising platforms for cancer biomarker development. Effective isolation of ultra-pure EVs for downstream analyses is key for EV-based liquid biopsy development. However, current EV isolation methods such as ultracentrifugation (UC) and other commercialized EV isolation kits are lackluster because of damage to EVs, length of time required, and low EV recovery rates. In response, we developed an “GET EV” kit which is based on the principles of lipid energy states, also known as the aqueous two-phase system (ATPS) to isolate EVs from any media. Nanoscale flow cytometry (nFC) analysis revealed that ATPS has greater EV enrichment capability (21.4 × vs. 10.9 × times fold enrichment) and higher EV recovery efficiency (97.6% vs. 69.3% recovery) than UC. Other EV isolation kits were tested and were inferior to ATPS in terms of EV recovery and EV-RNA recovery. EV subpopulations as determined by EV biomarkers (CD9, CD63, CD81, etc.) were confirmed by nFC. “Omics” studies (small RNA sequencing and proteomics) also confirmed the presence of expected EV markers. We developed an RNA-based liquid biopsy for Neuroendocrine Neoplasms (NENs) by quantitating the presence of EVs containing miR-375, an established biomarker for NENs. Using the GET EVs kit, we isolated EVs from healthy volunteer and patient plasma samples of NEN patients. RT-qPCR demonstrated enriched expression of miR-375 in EVs isolated from Lung and GI NEN patient plasma samples. Our study establishes the use of GET EV kits to efficiently, rapidly, and gently isolate EVs from small plasma samples (250 uL). This is a low-cost innovation that will finally enable the development of other RNA-based Liquid Biopsies for other disease sites with significant diagnostic and prognostic implications. Citation Format: Boyang Su, Morteza Jeyhani, Xiaojing Yang, Jina Nanayakkara, Reese Wunsche, Neil Renwich, Scott Tsai, Hon Leong. A low-cost kit for gentle, effective and timely extracellular vesicle (GET EVs) isolation: Accelerating development of RNA-based liquid biopsies for neuroendocrine neoplasms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3624.

Hypoalbuminemia, but not derived neutrophil to lymphocyte ratio (dNLR), predicts overall survival in neuroendocrine tumours undergoing peptide receptor radionuclide therapy: A retrospective, cohort study of 557 patients.

Several inflammation scores have shown association with survival outcomes for patients with neuroendocrine tumours (NET) treated with peptide receptor radionuclide therapy (PRRT). However, whether these scores add value to established prognostic factors remains unknown. In this retrospective, cohort study of 557 NET patients undergoing PRRT in a tertiary referral centre from 2005 to 2015, we examined inflammatory markers and scores previously associated with cancer outcomes, using Cox proportional hazard models and Akaike's information criterion. Lower albumin (hazard ratio [95% confidence interval], .91 [.87-.95] per unit), as well as higher C-reactive protein (CRP; 1.02 [1.01-1.02]), Glasgow Prognostic Score (GPS; 1 vs. 0: 1.67 [1.14-2.44], 2 vs. 0 3.60 [2.24-5.79]), CRP/albumin ratio (1.84 [1.43-2.37]) and platelet count (Plt) × CRP, but not white blood cell, neutrophil and thrombocyte counts or derived neutrophil to lymphocyte ratio (dNLR), were associated with shorter median overall survival (OS) in an adjusted analysis. The addition of parameters based on albumin and CRP, but not dNLR, to a base model including age, chromogranin A, the cell proliferation marker Ki-67, performance status, tumour site and previous treatments improved the predictive accuracy of the base model. In an exploratory analysis of patients with available erythrocyte sedimentation rate (ESR) and CRP, ESR emerged as the most powerful predictor. When added to a prognostic model for OS in NET patients treated with PRRT, most inflammation scores further improved the model. Albumin was the single marker adding most value to the set of established prognostic markers, whereas dNLR did not seem to improve the model's prognostic ability.

Plasma tryptophan pathway metabolites quantified by liquid chromatography-tandem mass spectrometry as biomarkers in neuroendocrine tumor patients.

A good and accessible biomarker is of great clinical value in neuroendocrine tumor (NET) patients, especially considering its frequently indolent nature and long-term follow-up. Plasma chromogranin A (CgA) and 5-hydroxyindoleacetic acid (5-HIAA) are currently used as biomarkers in NET, but their sensitivity and specificity are restricted. 5-HIAA is the main metabolite of serotonin, an important neurotransmitter of the tryptophan pathway. The aim of this study is to estabish a sensitive and accurate method for the quantification of tryptophan pathway metabolites in plasma. We further aimed to evaluate its utility as a clinical tool in NET disease. We obtained plasma samples from NET patients and healthy controls recruited from the University Hospital of North Norway, Tromsø. Samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and eight metabolites of the tryptophan pathway were quantified. We included 130 NET patients (72/130 small intestinal [SI] NET, 35/130 pancreatic NET, 23/130 other origin) and 20 healthy controls. In the SI-NET group, 26/72 patients presented with symptoms of carcinoid syndrome (CS). We found that combining tryptophan metabolites into a serotonin/kynurenine pathway ratio improved diagnostic sensitivity (92.3%) and specificity (100%) in detecting CS patients from healthy controls compared with plasma 5-HIAA alone (sensitivity 84.6%/specificity 100%). Further, a clinical marker based on the combination of plasma serotonin, 5-HIAA, and 5OH-tryptophan, increased diagnostic capacity identifying NET patients with metastasized disease from healthy controls compared with singular plasma 5-HIAA, serotonin, or CgA. In addition, this marker was positive in 61% of curatively operated SI-NET patients compared with only 10% of healthy controls (p < .001). Our results indicate that simultaneous quantification of several tryptophan metabolites in plasma, using LC-MS/MS, may represent a clinically useful diagnostic tool in NET disease.

Positive Expression of Paired Box 5 (Pax5) was Associated with Age, Tumor Location, and Tumor Size of Patients with Gastrointestinal Neuroendocrine Tumors (NETs)

Background: Neuroendocrine tumors (NETs) can occur in most human epithelial organs, however, there are few studies on digestive system NETs. Aims: The study aims to analyze Pax5 expression in digestive tract NETs and discuss its diagnostic significance. Methods: This study included 64 cases of NETs diagnosed from 2019 to 2020. Expressions of paired box 5 (Pax5), CD56, synaptophysin (Syn), and chromogranin (CgA) were detected using the immunohistochemical assay. Clinicopathological parameters, including tumor location, histological classification, depth of infiltration, tumor diameter, lymph node metastasis, vascular tumor thrombus, and nerve invasion, were determined in Pax5 positive and negative patients. Spearman correlation analysis was performed to analyze the correlation between Pax5 and CD56, Syn, and CgA. Results: The positive rate of Pax5 expression in patients with NETs was 46.9% (30/64). There were more patients ≥60 years illustrating positive expression of Pax5 compared to those patients &lt;60 years (χ2=8.438, P=0.004). There were significant differences in histological classification between Pax5 positive expression patients and Pax5 negative expression patients (χ2=17.639, P=0.011). Significant Pax5 positive expression patients demonstrated tumor size ≥3 cm, compared to Pax5 negative expression patients (χ2=6.764, P=0.009). Therefore, positive Pax5 expression was related to age, histological classification, and tumor size of NETs patients. Pax5 expression in digestive system NETs was not correlated with CD56 (χ2=0.233, r=0.024, P=0.853), Syn (χ2=0.635, r=0.047, P=0.715), CgA (χ2=2.346, r=0.170, P=0.179). Conclusions: Positive expression of Pax5 was related to age, tumor location, and tumor size of NETs patients. Pax5 can be used in combination with common immune markers (CD56/Syn/CgA) and can improve the diagnostic accuracy of digestive system NETs.

Real-world 177Lu-DOTATATE peptide receptor radionuclide therapy: Treatment outcomes with dosing variations and in non-midgut neuroendocrine tumors.

593 Background: Peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE has been used for neuroendocrine tumors (NETs) since its approval in the United States based on demonstrated progression-free survival benefit in grade 1-2 midgut NETs. The recommended dosing is 7.4 GBq (200 mCi) every 8 weeks for 4 doses in total. We examined the post-PRRT outcomes with dosing variations and in patients with non-midgut NETs. Methods: The medical records of 108 PRRT-naïve NET patients who received at least one cycle of PRRT at a single academic institution were reviewed. Among the patients with Ki-67 index ≤ 20%, progression-free survival (PFS) and overall survival (OS) were compared between midgut and non-midgut NETs. Among the patients who did not develop disease progression or mortality during the treatment course, PFS and OS were compared based on dosing variations. Dosing variations were defined as "reduced” (50% of 7.4 GBq/cycle), “delayed” (&gt;12 weeks between cycles), or “fewer” (&lt;4 cycles) doses. Kaplan-Meier survival analysis with log-rank test was used for statistical analysis. Results: Median clinical follow-up was 18.7 months, during which disease progression and death occurred in 54 (50%) and 20 (18%) patients, respectively. Among the 98 patients with Ki-67 index ≤ 20%, those with non-midgut tumors (n=55) showed significantly shorter PFS compared to those with midgut tumors (n=43) with the hazard ratio of 2.0 ( P=0.014, median of 15.6 vs. 26.9 mo.). No difference in OS was found between the two groups ( P=0.83). Among the 93 patients who did not develop disease progression or mortality during the course of PRRT, dosing variations were used in 23 patients. The types of dosing variations were “reduced” in 4 (17%) patients, “delayed” in 16 (70%) patients, and “fewer” in 7 (30%) patients. The reasons for dosing variations were hematologic in 9 (39%) patients, hepatic in 2 (9%) patients, renal in 1 (4%) patient, other medical in 3 (13%) patients, functional in 3 (13%) patients, and logistical in 6 (26%) patients. No difference in PFS ( P=0.20) or OS ( P=0.24) was found based on the presence or absence of dosing variations. Conclusions: Patients with non-midgut NETs show approximately twice the rate of disease progression over time following PRRT than those with midgut NETs. Administering reduced, delayed, or fewer doses of PRRT may still offer comparable benefit compared to the recommended dosing.

Acquisition Conditions for Lu-177 DOTATATE Imaging

We investigated imaging conditions for the distribution of lutetium oxodotreotide (Lu-177 DOTATATE) in the body during peptide receptor radionuclide therapy for neuroendocrine tumor (NET). We investigated imaging conditions using gamma rays emitted from the radionuclide. The gamma rays had energy peaks at 113 and 208 keV and characteristic X-rays at 56 keV. Image quality was compared by utilizing a combination of low–medium-energy general-purpose (LMEGP) and medium-energy general-purpose (MEGP) collimators. This study included the measurement of total spatial resolution (Full Width at Half Maximum) using a line source phantom. We compared the image quality of static images using a plane phantom and SPECT images using a cylindrical phantom. This comparison involved assessing recovery coefficient curves, count ratio, and %CV. Imaging evaluation was also performed on one NET patient. In phantom studies and the clinical study, comparing the combination of the three energy peaks (56 + 113 + 208 keV) using the LMEGP collimator and the conventional combination (113 + 208 keV) using the MEGP collimator revealed a count ratio of 1.9 times the maximum, stable %CV, and the best image quality.

Predicting the survival probability of functional neuroendocrine tumors treated with peptide receptor radionuclide therapy: Serbian experience.

Peptide receptor radionuclide therapy (PRRT) is a treatment option for well-differentiated, somatostatin receptor positive, unresectable or/and metastatic neuroendocrine tumors (NETs). Although high disease control rates seen with PRRT a significant number NET patients have a short progression-free interval, and currently, there is a deficiency of effective biomarkers to pre-identify these patients. This study is aimed at determining the prognostic significance of biomarkers on survival of patients with NETs in initial PRRT treatment. We retrospectively analyzed 51 patients with NETs treated with PRRT at the Department for nuclear medicine, University Clinical Center Kragujevac, Serbia, with a five-year follow-up. Eligible patients with confirmed inoperable NETs, were retrospectively evaluated hematological, blood-based inflammatory markers, biochemical markers and clinical characteristics on disease progression. In accordance with the progression og the disease, the patients were divided into two groups: progression group (n=18) and a non-progression group (n=33). Clinical data were compared between the two groups. A total of 51 patients (Md=60, age 25-75 years) were treated with PRRT, of whom 29 (56.86%) demonstrated stable disease, 4 (7.84%) demonstrated a partial response, and 14 (27.46%) demonstrated progressive disease and death was recorded in 4 (7.84%) patients. The mean PFS was a 36.22 months (95% CI 30.14-42.29) and the mean OS was 44.68 months (95% CI 37.40-51.97). Univariate logistic regression analysis displayed that age (p<0.05), functional tumors (p<0.05), absolute neutrophil count (p<0.05), neutrophil-lymphocyte ratio-NLR (p<0.05), C-reactive protein-CRP (p<0.05), CRP/Albumin (p<0.05), alanine aminotransferase-ALT (p<0.05), were risk factors for disease progression. Multivariate logistic regression analysis exhibited that functional tumors (p<0.001), age (p<0.05), CRP (p<0.05), and ALT (p<0.05), were independent risk factors for the disease progression in patients with NETs. Tumor functionality was the most powerful prognostic factor. The median PFS (11.86 ± 1.41 vs. 43.38 ± 3.16 months; p=0.001) and OS (21.81 ± 2.70 vs 53.86 ± 3.70, p=0.001) were significantly shorter in patients with functional than non-functional NETs respectively. The study's results suggest that tumor functionality, and certain biomarkers may serve as prognostic survival indicators for patients with NETs undergoing PRRT. The findings can potentially help to identify patients who are at higher risk of disease progression and tailor treatment strategies accordingly.

Long-term Nephrotoxicity after PRRT: Myth or Reality.

Rationale: The kidneys are commonly considered as the potential dose-limiting organ for peptide receptor radionuclide therapy (PRRT), making the risk of nephrotoxicity a primary concern. This retrospective analysis with prospective documentation and long-term follow-up aims to assess the risk of nephrotoxicity after PRRT in a large cohort of patients with neuroendocrine neoplasms (NENs) treated at our institution over the past 18 years. Methods: A total of 1361 NEN patients treated with 1-10 cycles of 177Lu-DOTA-TOC/-NOC/-TATE, 90Y-DOTA-TOC/-NOC/-TATE, DUO-PRRT (sequential administration of 90Y- and 177Lu-), or TANDEM-PRRT (combination of 90Y- and 177Lu- on the same day concomitantly) were included in this analysis. All parameters were prospectively documented in a structured database comprising over 250 items per patient and retrospectively analyzed. Kidney function, including serum creatinine, blood urea nitrogen, cGFR, and electrolytes, was evaluated before each PRRT cycle and during follow-up. Restaging was regularly performed at 6-month intervals until death. Treatment-related adverse events were graded according to the Common Terminology Criteria for Adverse Events (CTCAE v.5.0). Results: Between 2000 and 2018, a total of 5409 cycles of PRRT were administered to 1361 NEN patients. Follow-up after complete treatment was available for 1281 patients receiving 4709 cycles of PRRT, with a median follow-up time of 69.2 months (interquartile range, 32.8-110.5 months) and a maximum follow-up time of 175 months. Baseline creatinine levels were normal in 1039/1281 (81.1%) subjects, while grade 1 (G1) renal insufficiency was present in 221/1281 (17.3%) prior to PRRT. G2 was present in 19/1281 (1.5%), and G3 in 2/1281 (0.2%). After treatment, the proportion of G3/G4 grade patients only increased from 0.2% to 0.7%. Mean creatinine levels increased from a baseline of 0.90 ± 0.30 to 1.01 ± 0.57 mg/L (80.0 ± 26.7 to 89.4 ± 50.8 μmol/L) after treatment. In our main analysis cohort of 1244 patients (4576 cycles), 200 patients experienced an increase in CTCAE creatinine grade. Age, number of treatment cycles, type of radionuclides, and length of follow-up time were the main factors affecting CTCAE creatinine grading after treatment. When comparing the subgroups treated with different radionuclides, the risk of nephrotoxicity after 90Y treatment alone and the 90Y/177Lu combination group was higher than after 177Lu treatment alone. In the 90Y treatment subgroup, the two significant risk factors for an increased CTCAE creatinine grade were identified to be age (≥60) and a long follow-up time. Conclusions: This retrospective analysis with prospective documentation in a large cohort of 1281 NEN patients receiving 4709 cycles of PRRT co-administered with renal protection, treated through the individualized approach at a single institution over 18 years, did not reveal any evidence of long-term PRRT-related renal toxicity. The results of our study suggest that with the use of proper renal protection, nephrotoxicity due to PRRT is more likely a myth than a reality.

Outlook for 615 Small Intestinal Neuroendocrine Tumor Patients: Recurrence Risk after Surgery and Disease-Specific Survival in Advanced Disease.

Small intestinal neuroendocrine tumors (siNET) are one of the most common neuroendocrine neoplasms. Radical surgery is the only curative treatment. We utilized a single-center study including consecutive patients diagnosed from 2000 to 2020 and followed them until death or the end of study. Disease-specific survival and recurrence-free survival (RFS) were investigated by Cox regression analyses with the inclusion of prognostic factors. Aims/primary outcomes: We identified three groups: (1) disease specific-survival in the total cohort (group1), (2) RFS and disease-specific survival after intended radical surgery (group2), (3) disease specific-survival in patients with unresectable disease or residual tumor after primary resection (group3). In total, 615 patients, with a mean age (SD) 65 ± 11 years were included. Median (IQR) Ki-67 index was 4 (2-7)%. Median disease-specific survival in group1 was 130 months. Median RFS in group2 was 138 months with 5- and 10-year RFS rates of 72% and 59% with age, plasma chromogranin A (p-CgA) and Ki-67 index as prognostic factors. The ten year disease-specific survival rate in group2 was 86%. The median disease-specific survival in group3 was 85 months with age, Ki-67 index, p-CgA and primary tumor resection as prognostic factors. When proliferation was expressed by WHO grade, no difference was observed between G1 vs. G2 for any of the primary outcomes. Recurrence rates remained high 5-10 years after surgery (group2) supporting long-term follow-up. Median disease-specific survival in patient with unresectable disease (group3) was 7 years, with a favorable impact of primary tumor resection. Our data does not support the current grading system since no significant prognostic information was detected in G1 vs. G2 tumors.

Incidence of second malignancies in patients with thymic carcinoma and thymic neuroendocrine tumor

ObjectivesThymic carcinoma and thymic neuroendocrine tumor (NET) are rare and are more likely to develop second malignancies. The purpose of this study was to explore the incidence and lifetime risk of second malignancies in thymic carcinoma and thymic NET.MethodsThe standardized incidence ratio (SIR) and the age-adjusted cancer incidence of the thymic carcinoma and thymic NET patients with second malignancies were retrospectively calculated by using the Surveillance, Epidemiology, and End Results (SEER) database. Prognosis results were also determined by Kaplan–Meier analysis and Cox regression.Results1130 patients with thymic carcinoma (73 patients had second malignancies) and 263 patients with thymic NET (19 patients had second malignancies) from 2000 to 2018 are included. Patients with thymic carcinoma (SIR: 1.36, 95% CI 1.08–1.69) and with thymic NET (SIR: 1.73, 95% CI 1.13–2.54) demonstrate an increased overall risk of developing second malignancies in various organ systems. The age-adjusted cancer incidence of second malignancies in patients with thymic carcinoma is 3058.48 per 100,000 persons (4178.46 per 100,000 persons in patients with thymic NET). Age at diagnosis is a significant risk factor for the development of second malignancies.ConclusionThe incidence of second malignancies in patients with thymic carcinoma and thymic NET is significantly higher than the patients in the normal population. The occurrence of second malignancies is not related to the use of different treatments. It is important to extend the follow-up period and add other screening methods.

Prediction of 177Lu-DOTATATE Therapy Outcomes in Neuroendocrine Tumor Patients Using Semi-Automatic Tumor Delineation on 68Ga-DOTATATE PET/CT.

Treatment of metastatic neuroendocrine tumors (NET) with 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) results in favorable response only in a subset of patients. We investigated the prognostic value of quantitative pre-treatment semi-automatic 68Ga-DOTATATE PET/CT analysis in NET patients treated with PRRT. The medical records of 94 NET patients who received at least one cycle of PRRT at a single institution were retrospectively reviewed. On each pre-treatment 68Ga-DOTATATE PET/CT, the total tumor volume (TTV), maximum tumor standardized uptake value for the patient (SUVmax), and average uptake in the lesion with the lowest radiotracer uptake (SUVmin) were determined with a semi-automatic tumor delineation method. Progression-free survival (PFS) and overall survival (OS) among the patients were compared based on optimal cutoff values for the imaging parameters. On Kaplan-Meier analysis and univariate Cox regression, significantly shorter PFS was observed in patients with lower SUVmax, lower SUVmin, and higher TTV. On multivariate Cox regression, lower SUVmin and higher TTV remained predictive of shorter PFS. Only higher TTV was found to be predictive of shorter OS on Kaplan-Meier and Cox regression analyses. In a post hoc Kaplan-Meier analysis, patients with at least one high-risk feature (low SUVmin or high TTV) showed shorter PFS and OS, which may be the most convenient parameter to measure in clinical practice. The tumor volume and lowest lesion uptake on 68Ga-DOTATATE PET/CT can predict disease progression following PRRT in NET patients, with the former also predictive of overall survival. NET patients at risk for poor outcomes following PRRT can be identified with semi-automated quantitative analysis of 68Ga-DOTATATE PET/CT.

Impact of sex on treatment decisions and outcome in patients with neuroendocrine neoplasms.

Sex differences affect the management of several diseases in both male and female patients. However, the influence of sex on neuroendocrine neoplasms (NENs) has been scarcely investigated. Thus, this study aimed to compare tumor characteristics, treatment decisions, and overall survival in patients with NENs, stratified by sex. The retrospective analysis of the SwissNET cohort covered NENs of gastroenteropancreatic, pulmonary, or unknown origin from July 2014 to September 2022. The analysis included 1985 patients (46% female and 54% male). No significant difference in tumor grading was found between male and female patients. However, male patients presented with higher staging at time of diagnosis and with more lymph node and bone metastases. Surgery was performed more often in female compared to male patients (73.4% vs 68.7%, P = 0.023). Male patients received peptide receptor nuclide therapy (PRRT) earlier than female patients (7.8 months vs 13.1 months from time of diagnosis, P = 0.003). The median overall survival was significantly shorter for male compared to female patients (male: 18 years, female: not reached, P < 0.001, hazard ratio (HR) 1.55 (1.19-2.01), P = 0.001). Multivariable analyses revealed advanced age (HR 1.02 (1.01-1.04)), cancer of unknown origin (HR 2.01 (1.09-3.70)), higher grading (G3: HR 6.74 (4.22-10.76)), having metastases at the time of diagnosis (HR 2.11 (1.47-3.02)), and surgical treatment (HR 0.67 (0.48-0.93)) as independent predictors for overall survival. In conclusion, male sex was associated with worse outcome in NEN patients, likely due to more advanced tumor stage at the time of diagnosis. Further investigations are required to understand the underlying mechanisms of these sex differences.