1167P - Outcomes of local and systemic treatment in primary hepatic neuroendocrine neoplasms (PHNEN)

Background

Liver involvement in neuroendocrine neoplasms (NEN) most commonly encompasses metastases from other organs or from an unknown primary. However, the current WHO classification defines primary hepatic NEN (PHNEN) arising in the liver as a distinct entity. With only few cases of PHNEN reported and difficulty to discern them from hepatic metastases, evidence on optimal management is very limited.

Methods

Retrospective review of the combined prospective and retrospective databases of two high-volume NEN centers for PHNEN presenting between 08/1996 and 10/2023.

Results

Among over 2500 patients in the databases, 38 patients with PHNEN could be identified. Median follow-up was 40.7 months. Histologies were NET G1 (n=6), NET G2 (n=17), NET G3 (n=3), NEC G3 (n=11) and MiNEN (n=1). Resection of the hepatic primary was performed in 23 patients with a median recurrence-free survival of 115.9 months. 5 patients received liver transplantation, median RFS was 139.1 months. TACE with streptozotocin (STZ) led to a PR in 3 of 4 patients, mostly in multimodal treatment concepts. Monotherapy with a somatostatin analogue (SSA) was administered to 7 evaluable patients, all with stable disease (SD) and a median PFS of 14.0 months. 5 evaluable patients received alkylating-based chemotherapy with a median PFS of 16.5 months and 1 partial remission (PR) under STZ+5-FU. Of 4 evaluable patients under peptide receptor radionuclide therapy (PRRT), 2 showed a PR, 1 an SD and 1 a mixed response. Other systemic treatments with notable activity included sunitinib (1 PR) and FOLFOX+bevacizumab (1 PR). Platinum-based chemotherapy was applied in 9 NEN G3 patients with only 2 PRs and 1 SD as best responses and the remaining tumors progressing, with a median progression-free survival of 2.5 months. The median overall survival of the whole cohort was 133.9 months, with 4.2 months in NEC G3 and MiNEN vs. 133.9 months in NET G1-3 (p<0.0001).

Conclusions

Both primary tumor resection and liver transplantation can lead to long-time RFS in PHNEN. While STZ-based TACE, SSAs, PRRT and alkylating-based chemotherapy showed encouraging activity in well-differentiated PHNEN, efficacy of platinum-based chemotherapy in G3 PHNEN was limited. Prognosis was largely determined by grading and differentiation.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Heidelberg University Hospital.

Funding

Has not received any funding.

Disclosure

L. Apostolidis: Financial Interests, Personal, Invited Speaker: Ipsen, BMS; Financial Interests, Personal, Advisory Board: Novartis; Financial Interests, Institutional, Local PI: Camurus, Roche; Non-Financial Interests, Member: ENETS, DGEM, DKG, AIO, DGHO. L. de Mestier du Bourg: Financial Interests, Personal, Advisory Board: Adacap, Ipsen, Esteve, Sirtex, Servier; Financial Interests, Personal, Invited Speaker: Viatris. All other authors have declared no conflicts of interest.