Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2026

MAD beyond tumour grade: baseline radiomics predicts survival in advanced GEP-NENs undergoing PRRT (142940)

Jonathan Ben Daniel 1 , Jacky Wei-Ting Chen 1 , Kevin C Guan 1 , Elizabeth J Bernard 2 , David L Chan 1 3
  1. The University of Sydney, Sydney, NSW, Australia
  2. Medical Imaging & Nuclear Medicine, Royal North Shore Hospital, Sydney, NSW, Australia
  3. Medical Oncology, Royal North Shore Hospital, Sydney, NSW, Australia

Aim: Neuroendocrine Neoplasms (NENs) are a group of heterogeneous cancers which are increasing in incidence. Grading of neuroendocrine neoplasms relies on single-site biopsies, which are susceptible to sampling errors and fail to capture intra-patient tumour heterogeneity. This study aimed to evaluate the prognostic utility of baseline radiomic (image-based biomarker) measures on baseline somatostatin receptor (SSTR) PET, compared with established clinicopathological parameters, in patients with advanced gastroenteropancreatic neuroendocrine tumours (GEP-NENs) undergoing peptide receptor radionuclide therapy (PRRT).

Methods: We evaluated 79 patients with advanced GEP-NENs undergoing 177Lu-DOTATATE PRRT who underwent baseline 68Ga-DOTATATE PET/CT imaging. A cutoff extrapolated from PERCIST criteria (1.5 * SUV + 2SD) was derived from a normal liver region of interest for hepatic lesions, and a flat 4 SUV cutoff for extrahepatic lesions. All contours were checked by an experienced nuclear medicine physician. First-order radiomic features were extracted from contours using PyRadiomics. After feature selection, remaining radiomics variables were assessed against standard clinical covariates with multivariable Cox regression for overall survival (OS) and progression-free survival (PFS).

Results: Mean Absolute Deviation (MAD) was identified as the sole significant prognostic radiomic feature. In multivariable analysis, MAD remained an independent predictor of both OS (HR=0.838, p=0.0016) and PFS (HR = 0.896, p = 0.034). Conversely, grade and Ki-67 index did not demonstrate independent prognostic significance in multivariable analysis. Patients stratified by median MAD into high versus low strata demonstrated significantly prolonged median OS (80.3 vs. 53.2 months, HR = 0.39, 95% CI: 0.22–0.72, p = 0.0017) and median PFS (52.3 vs.37.5 months, HR = 0.59, 95% CI: 0.35–0.99, p = 0.0440).

Conclusion: Total tumour burden MAD in 68Ga-DOTATATE PET is a strong predictor for survival in advanced GEPNENs treated with PRRT. These findings warrant prospective validation.