Endocrine Abstracts

Introduction: Mixed non-neuroendocrine and neuroendocrine neoplasms (MiNENs) of gastrointestinal tract are rare tumours with characteristic histological features include at least 30% of both neuroendocrine and non-neuroendocrine components of the whole neoplasm. They are usually treated with surgical resection and chemotherapy in advanced disease. However, there is scarcity of data for the use of peptide receptor radionuclide therapy (PRRT) in these tumours.

Case presentation: An 82-year-old asymptomatic female referred to the neuroendocrine department in February 2023 following an incidental finding of liver lesions found on routine investigations for systolic murmur. Radiological investigations revealed bi-lobar liver metastases with unknown primary. Histology from the liver biopsy confirmed MiNENs with the predominant component (up to 60%) being grade 2 well differentiated neuroendocrine tumour (NET) with Ki67 of 19% and a smaller component (up to 30%) of well to moderately differentiated adenocarcinoma of pancreaticobiliary origin. Functional Imaging showed ⁶⁸Ga DOTATATE PET-CT avid bi-lobar liver metastases with no extrahepatic focus of activity, and there was no FDG PET-CT avid activity within the liver metastases. She was initially started on Lancreotide 120mg Auto gel every 28 days however the liver tumours progressed, and this was stopped in November 2023. After review in the MDT in view of the strong avid ⁶⁸Ga DOTATATE uptake she proceeded to four cycles of ¹⁷⁷Lu-DOTATATE therapy between November 2023 and June 2024. Post PRRT her repeat imaging showed reduction in the size of liver metastases (index lesions segment 4 and 3 reduced from 26mm to 18 mm and 21mm to 14 mm respectively). She remained well post PRRT treatment.

Conclusion: PRRT is currently not used in treatment protocol for the management of MiNEN, however, it could be a treatment option in patients with MiNEN where there is a predominant component of well differentiated NET with ⁶⁸Ga DOTATATE avid lesions.