Value of Tumor Growth Rate (TGR) as an Early Biomarker Predictor of Patients’ Outcome in Neuroendocrine Tumors (NET)—The GREPONET Study

Introduction Tumor growth rate (TGR; percent size change per month [%/m]) is postulated to be an early radiological biomarker to overcome limitations of RECIST. This study aimed to assess the impact of TGR in neuroendocrine tumors (NETs) and potential clinical and therapeutic applications. Materials and Methods Patients (pts) with advanced grade (G) 1/2 NETs from the pancreas or small bowel initiating systemic treatment (ST) or watch and wait (WW) were eligible. Baseline and follow‐up scans were retrospectively reviewed to calculate TGR at pretreatment (TGR0), first follow‐up (TGRfirst), and 3(±1) months of study entry (TGR3m). Results Out of 905 pts screened, 222 were eligible. Best TGRfirst (222 pts) cutoff was 0.8 (area under the curve, 0.74). When applied to TGR3m (103 pts), pts with TGR3m