Prognostic value of 68Ga-DOTANOC PET/CT SUVmax in patients with neuroendocrine tumors of the pancreas

Abstract

This study was performed to investigate the role of 68Ga-DOTANOC SUVmax as a potential prognostic factor in patients with pancreatic neuroendocrine tumor (pNET). Methods: Among the patients who underwent 68Ga-DOTANOC PET/CT, we retrospectively collected the data of those who had G1 or G2 pNET (2010 World Health Organization classification), presented with disease on PET/CT and CT, and had at least 6 mo of follow-up. Patients with multiple endocrine neoplasia were excluded. Results: Overall, 43 patients were included. No significant differences in SUVmax were observed with respect to sex, tumor syndrome, stage, World Health Organization classification, or Ki-67. During follow-up (median, 20 mo), 11 patients (35.6%; median, 33 mo; interquartile range, 20-48 mo) had stable disease and 32 (74.4%; median, 19 mo; interquartile range, 14-26 mo) had progressive disease. SUVmax at 24 mo of follow-up was significantly higher (P 5 0.022) in patients with stable disease than in patients with progressive disease. The best SUVmax cutoff ranged from 37.8 to 38.0. The major risk factors for progression included an SUVmax of no more than 37.8 (hazard ratio, 3.09; P5 0.003), a Ki-67 of more than 5%(hazard ratio, 2.89; P 5 0.009), and medical therapy alone (hazard ratio, 2.36; P 5 0.018). Advanced stage (IV) (P 5 0.026), an SUVmax of less than 37.8 (P 5 0.043), and medical therapy alone (P 5 0.015) were also confirmed at multivariate analysis. Median progression-free survival was 23 mo. Significant differences in progression-free survival were observed in relationship to Ki-67 (median, 45 mo for Ki-67 ≤ 5% and 20 mo for Ki-67. 5%; P 5 0.005), SUVmax (<37.8 vs. >38.0: 16.0 vs. 27.0 mo; P 5 0.002), and type of therapy (medical vs. peptide receptor radionuclide therapy: 16.0 vs. 26.0 mo; P 5 0.014). Conclusion: 68Ga-DOTANOC SUVmax is a relevant prognostic factor in patients with G1 and G2 pNET, and its routine use will improve disease characterization and management in these patients, who may present with atypical cases showing heterogeneous clinical behavior.