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Dysregulated hormonal production remains a challenge in the management of neuroendocrine neoplasms (NEN). We report 4 cases of patients with functional NEN treated with stereotactic body radiation therapy (SBRT) to either the primary/dominant metastatic site of disease or the end organ of hormonal release. No significant toxicities were observed during or after treatment. Each patient has had biochemical, clinical and radiographic response to therapy, providing proof of concept that SBRT is an effective therapeutic strategy for functional neuroendocrine neoplasms. [ABSTRACT FROM AUTHOR]

Important progress has been made over the last decade in the classification, imaging, and treatment of neuroendocrine neoplasm (NENs), with several new agents approved for use. Although the treatment options available for patients with well-differentiated neuroendocrine tumors (NETs) have greatly expanded, the rapidly changing landscape has presented several unanswered questions about how best to optimize, sequence, and individualize therapy. Perhaps the most important development over the last decade has been the approval of 177Lu-DOTATATE for treatment of gastroenteropancreatic-NETs, raising questions around optimal sequencing of peptide receptor radionuclide therapy (PRRT) relative to other therapeutic options, the role of re-treatment with PRRT, and whether PRRT can be further optimized through use of dosimetry among other approaches. The NET Task Force of the National Cancer Institute GI Steering Committee convened a clinical trial planning meeting in 2021 with multidisciplinary experts from academia, the federal government, industry, and patient advocates to develop NET clinical trials in the era of PRRT. Key clinical trial recommendations for development included 1) PRRT re-treatment, 2) PRRT and immunotherapy combinations, 3) PRRT and DNA damage repair inhibitor combinations, 4) treatment for liver-dominant disease, 5) treatment for PRRT-resistant disease, and 6) dosimetry-modified PRRT. [ABSTRACT FROM AUTHOR]

There is an increased risk of second primary cancers (SPCs) after neuroendocrine tumor (NET) diagnosis. The clinical significance of SPCs in this population is unknown. The purpose of this study was to evaluate the association between SPCs after NET diagnosis and survival. We performed a population-based, retrospective cohort study of NET patients (gastrointestinal, pancreatic, or lung primary) from 2000 to 2016 using the Surveillance, Epidemiology, and End Results database. Cox regression models assessed the association between SPCs and NET-specific (NET-SS), cancer-specific (CSS), and overall survival (OS). Of 58,553 NET patients, 7.9% experienced an SPC. SPCs were associated with worse OS (hazard ratio (HR) 2.14, 95% CI 1.94-2.36) and CSS (HR 2.31, 95% CI 2.06-2.59) with no difference in NET-SS (HR 1.04, 95% CI 0.87-1.23). Stratified analyses by histologic grade showed similar results for well and moderately differentiated NETs, but no difference in OS or CSS for poorly differentiated NETs (P > 0.05). In stratified analyses by NET site, SPCs were associated with worse OS (HR 3.41, 95% CI 3.01-3.87) and CSS (HR 4.96, 95% CI 4.28-5.74) in gastrointestinal NETs and worse OS (HR 1.25, 95% CI 1.03-1.52) with no difference in CSS (HR 1.08, 95% CI 0.85-1.36) in lung NETs. SPCs were not associated with a difference in OS or CSS in pancreatic NETs (P > 0.05). In conclusion, SPCs after NETs were associated with inferior OS and CSS compared to no SPC but were not associated with NET-SS. These data highlight the need for long-term follow-up in NETs to include the detection of SPCs to ensure early diagnosis and timely management. [ABSTRACT FROM AUTHOR]

High-grade neuroendocrine neoplasms are a rare disease entity and account for approximately 10% of all neuroendocrine neoplasms. Because of their rarity, there is an overall lack of prospectively collected data available to advise practitioners as to how best to manage these patients. As a result, best practices are largely based on expert opinion. Recently, a distinction was made between well-differentiated high-grade (G3) neuroendocrine tumors and poorly differentiated neuroendocrine carcinomas, and with this, pathologic details, appropriate imaging practices and treatment have become more complex. In an effort to provide practitioners with the best gui dance for the management of patients with high-grade neuroendocrine neoplasms of the gastrointestinal tract, pancreas, and gynecologic system, the North American Neuroendocrine Tumor Society convened a panel of experts to develop a set of recommendations and a treatment algorithm that may be used by practitioners for the care of these patients. Here, we provide consensus recommendations from the panel on pathology, imaging practices, management of localized disease, management of metastatic disease and surveillance and draw key distinctions as to the approach that should be utilized in patients with well-differentiated G3 neuroendocrine tumors vs poorly differentiated neuroendocrine carcinomas. [ABSTRACT FROM AUTHOR]

Introduction: Liver metastases are common in patients with neuroendocrine neoplasms. The role of stereotactic ablative radiotherapy (SABR) is not well understood in this population. Objective: The objective of this study was to evaluate the safety and efficacy of SABR in treating well-differentiated neuroendocrine liver metastases (WD-NELM). Methods: A retrospective review of patients with WD-NELM treated with SABR was conducted between January 2015 and July 2019. Demographic, treatment, and clinical/radiographic follow-up data were abstracted. RECIST 1.1 criteria were applied to each individual target to evaluate the response to treatment. Local control (LC) and progression-free survival (PFS) were determined using the Kaplan-Meier methodology. Toxicity was reported according to the CTCAE v5.0. Results: Twenty-five patients with a total of 53 liver metastases treated with SABR were identified. Most patients (68%) had midgut tumors, were grade 2 (80%), and had high-volume intrahepatic and/or extrahepatic disease (76%). The median number of liver metastases treated was 2, with a median size of 2.5 cm. The median radiation dose delivered was 50 Gy/5 fractions. The median follow-up was 14 months; 24 of the 25 patients were alive at the time of analysis. The objective response rate was 32%, with improvement or stability in 96% of lesions treated. The median time to best response was 9 months. The 1-year LC and PFS were 92 and 44%, respectively. No grade 3/4 acute or late toxicity was identified. Conclusions: Liver SABR is a safe and promising means of providing LC for WD-NELM. This treatment modality should be evaluated in selected patients in concert with strategies to manage systemic disease. [ABSTRACT FROM AUTHOR]