RT Journal Article SR Electronic T1 68Ga-DOTATATE PET/CT for the Early Prediction of Response to Somatostatin Receptor–Mediated Radionuclide Therapy in Patients with Well-Differentiated Neuroendocrine Tumors JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1349 OP 1356 DO 10.2967/jnumed.110.075002 VO 51 IS 9 A1 Alexander R. Haug A1 Christoph J. Auernhammer A1 Björn Wängler A1 Gerwin P. Schmidt A1 Christopher Uebleis A1 Burkhard Göke A1 Paul Cumming A1 Peter Bartenstein A1 Reinhold Tiling A1 Marcus Hacker YR 2010 UL http://jnm.snmjournals.org/content/51/9/1349.abstract AB We aimed to evaluate 68Ga-DOTATATE PET/CT for the early prediction of time to progression and clinical outcome after a first cycle of peptide receptor radionuclide treatment (PRRT) in a cohort of patients with well-differentiated neuroendocrine tumors. Methods: Thirty-three consecutive patients (22 men and 11 women; mean age ± SD, 57.8 ± 12.1 y) were investigated at baseline and again 3 mo after initiation of the first cycle of PRRT. 68Ga-DOTATATE receptor expression was assessed using 2 measures of standardized uptake value (SUV): maximum SUV (SUVmax) and tumor-to-spleen SUV ratio (SUVT/S). Percentage change in SUV scores after PRRT relative to baseline (ΔSUV) was calculated. After completing 1–3 cycles of PRRT, patients entered the follow-up study, for estimation of time to progression. According to the Response Evaluation Criteria in Solid Tumors, progression was defined on the basis of contrast-enhanced CT. Clinical symptoms, as well as the tumor markers chromogranin A and neuron-specific enolase, were also recorded during regular follow-up visits. Results: The 23 of 31 patients with decreased SUVT/S after the first PRRT cycle had longer progression-free survival than did the 8 of 31 patients with stable or increased scores (median survival not reached vs. 6 mo, P = 0.002). For the 18 of 33 patients showing a reduction in SUVmax, there was no significant difference in progression-free survival (median survival not reached vs. 14 mo, P = 0.22). Multivariate regression analysis identified SUVT/S as the only independent predictor for tumor progression during follow-up. In the 17 of 33 patients with clinical symptoms before PRRT, ΔSUVT/S correlated with clinical improvement (r = 0.52, P < 0.05), whereas ΔSUVmax did not (r = 0.42, P = 0.10). Changes in the tumor markers (chromogranin A and neuron-specific enolase) did not predict ΔSUV scores, clinical improvement, or time to progression. Conclusion: Decreased 68Ga-DOTATATE uptake in tumors after the first cycle of PRRT predicted time to progression and correlated with an improvement in clinical symptoms among patients with well-differentiated neuroendocrine tumors; ΔSUVT/S was superior to ΔSUVmax for prediction of outcome.