Treatment with Octreotide Does Not Reduce Tumor Uptake of 68Ga-DOTATATE as Measured by PET/CT in Patients with Neuroendocrine Tumors

Abstract

We hypothesized that ⁶⁸Ga-DOTATATE uptake of neuroendocrine tumors is sensitive to therapy with a nonradioactive somatostatin analog. Methods: ⁶⁸Ga-DOTATATE PET/CT was used to examine 105 patients, 35 of whom had been pretreated with long-acting octreotide. The maximum standardized uptake value (SUV_max) of target tissues, as well as metastases, was compared between the groups of patients with (group 1) and without (group 2) octreotide treatment. Results: The SUV_max of the spleen and liver was significantly lower in group 1 than in group 2 (both P < 0.001). There were no significant group differences in SUV_max for primary tumors (28.6 ± 6.8 vs. 32.9 ± 31.5) or metastases in the liver (27.2 ± 14.8 vs. 25.7 ± 10.7), lymph nodes (41.4 ± 19.5 vs. 25.0 ± 6.3), or skeleton (39.5 ± 22.0 vs. 15.4 ± 7.8). In 9 patients available for intraindividual comparison, tumor uptake was unaffected by treatment with somatostatin analogs (21.7 vs. 20.6; P = 0.93). Conclusion: Treatment with a long-acting somatostatin analog did not significantly reduce ⁶⁸Ga-DOTATATE binding in neuroendocrine tumors but tended to improve the tumor-to-background ratio.