Abstract 1184P
Background
Although grade 3 neuroendocrine tumor (NET) represents a new category officially recognized in the 2019 World Health Organization classification of gastro-entero-pancreatic (GEP) neuroendocrine neoplasms (NENs), its clinical management is not universally shared. We reported a retrospective series of NET G3 patients (pts) clinically managed at our NET referral center.
Methods
Clinical and biological features of NET G3 pts treated at the European Institute of Oncology (Milan) between 2015 and 2019 were retrospectively analysed and correlated with clinical outcomes.
Results
Among 48 pts in total, 88% were GEP and 12% unknown-primary (UP). Median age was 56 years (range 26-87), males were 62%, 94% had synchronous metastases and median Ki67 label index was 30% (21-70). Seventy percent of pts had an upfront NET G3 (group A) whereas 30% had a NET G1/G2 at diagnosis that became a NET G3 later during the clinical history (group B). Pts with a Ki-67 ≤30% (58%) had significantly better overall survival (OS) (p=0.033) and a trend to a better progression free survival (PFS); those with a homogeneously versus inhomogeneously positive 68Gallium-Dota-Peptide Positron Emission Tomography (PET)/computed tomography (CT) showed a significantly better OS (p=0.004), PFS (p=0.036) and clinical benefit (CB) (considered as all stable disease, partial and complete responses) (p=0.031). A trend to a better OS and PFS was reported in pts with an inhomogeneous 18-fluorodeoxyglucose (FDG) -PET/CT compared with those with a homogeneously one. A significantly better OS was observed for negative and inhomogeneous versus homogeneous 18-FDG-PET/CT (p=0.029). Ki-67 on the hotspot or homogeneously expressed did not significantly condition clinical outcomes. While a trend to a better OS was reported in group B, group A pts showed a significantly better objective response rate, irrespective the treatment (p= 0.028).
Conclusions
Our retrospective analysis suggested that, in NET G3 population, the prognostic role of Ki-67, in terms of 30% cut-off and hotspot expression, and homogeneous/inhomogeneous radiotracers distribution of functional imaging could be a solid hypothesis to be prospectively investigated in more homogeneous population.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.