Nuklearmedizin 2022; 61(02): 189-190
DOI: 10.1055/s-0042-1746094
Abstracts | NuklearMedizin 2022
WIS-Poster
Radionuklidbatterie/Theranostics

Assessment of tumor response to therapy by somatostatin receptor (SSTR) PET/CT

Authors

  • V. Dinkel

    1   Klinikum rechts der Isar, Nuklearmedizin, München

  • A. von Werder

    2   Klinikum rechts der Isar, München

  • L. Steinhelfer

    2   Klinikum rechts der Isar, München

  • K. Knorr

    1   Klinikum rechts der Isar, Nuklearmedizin, München

  • W.A. Weber

    1   Klinikum rechts der Isar, Nuklearmedizin, München
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Ziel/Aim PET with radiolabeled somatostatin analogs is increasingly used to monitor tumor response to therapy in patients with neuroendocrine tumors (NETs). However, criteria for response assessment on SSTR PET have not been validated so far and it is unclear if response criteria used for FDG PET can also be applied to SSTR PET.

Methodik/Methods We retrospectively evaluated the pre- and post-therapeutic SSTR PET/CT scans of 44 consecutive NET patients (pts) who were treated with 2-4 cycles of PRRT with 177Lu-DOTA-TATE. Tumor response was assessed as described for FDG PET by the PERCIST criteria and correlated with progression free survival.

Ergebnisse/Results The 44 pts included 15 with pancreatic NETs, 14 with small intestinal NETs, and 15 with other NETs. 12 tumors were graded G1 and 32 G2. Response on SSTR PET/CT was CR, PR, SD, and PD, in 1, 25, 15 and 3 pts, respectively. Median follow-up time was 46.9 months during which a total of 29 pts progressed. Median PFS of all pts was 38.2 months and 1-year PFS 84%. There were no significant differences in PFS between PET responders (CR/PR), median survival 38.2 months, vs PET non-responders (SD/PD), median survival 36.4 months. Restricting the analysis to the subgroups of patients with G1 or G2 tumors, respectively, also revealed no significant PFS differences between PET responders and non-responders (G1: PFS 38.3 vs 31.6 months; G2: PFS 32.0 vs 40.1 months). When the analysis was limited to patients with pancreatic NETs there was a trend for longer PFS of responders (median PFS>50 months vs 14.7 months) but patient numbers of this subgroup are too small for definitive conclusions.

Schlussfolgerungen/Conclusions In this retrospective analysis tumor response according to PERCIST was not a prognostic factor for patients with NETs treated by PRRT. Other approaches for response assessment than PERCIST may be required to monitor treatment of NETs with SSTR PET.


Publication History

Article published online:
14 April 2022

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