Results of individual patient dosimetry in peptide receptor radionuclide therapy with 177Lu DOTA-TATE and 177Lu DOTA-NOC.
One of the few treatment options for inoperable neuroendocrine tumors (NET) is peptide receptor radiotherapy with somatostatin analogs. In this study, we compared the dosimetric parameter uptake, half-life (kinetics), and mean absorbed organ and tumor doses of (177)Lu DOTA-NOC and (177)Lu DOTA-TATE.


METHODS
Ninety-five (95) post-therapeutic dosimetric assessments using (177)Lu DOTA-TATE and 8 using (177)Lu DOTA-NOC in 69 patients with neuroendocrine tumors with high somatostatin receptor expression (verified by Ga-68 DOTA-NOC positron emission tomography/computed tomography) were analyzed. Dosimetric calculations were performed according to the Medical Internal Radiation Dose scheme.


RESULTS
(177)Lu DOTA-NOC showed a significantly (p < or = 0.05; sign test) higher uptake for whole-body and normal tissue, as compared to (177)Lu DOTA-TATE, leading to a significant higher whole-body dose of 0.07 mGy/ MBq for DOTA-NOC, as compared to 0.05 mGy/MBq for DOTA-TATE. Renal and spleen uptake and radiation doses were not significantly higher for DOTA-NOC. The uptake in tumor lesions and the mean absorbed tumor dose were higher for DOTA-TATE. The red marrow dose was approximately 0.2 Gy.


CONCLUSIONS
Our first results demonstrated that the higher in vitro affinity of DOTA-NOC leads to a higher uptake in normal tissues and, therefore, to an increase in the whole-body dose. The high interpatient variability of these results makes an individual patient dosimetry obligatory.
Wehrmann
Christiane
C
Department of Nuclear Medicine/Center for P.E.T., Zentralklinik Bad Berka, Bad Berka, Germany.
Senftleben
Stefan
S
Zachert
Carolin
C
Müller
Dirk
D
Baum
Richard P
RP
D000328:Adult; D000368:Aged; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D005260:Female; D006573:Heterocyclic Compounds, 1-Ring / Q000627:therapeutic use; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D008187:Lutetium / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D049268:Positron-Emission Tomography; D011868:Radioisotopes / Q000627:therapeutic use*; D011878:Radiotherapy / Q000379:methods; D011879:Radiotherapy Dosage; D018000:Receptors, Peptide / Q000627:therapeutic use*; D014057:Tomography, X-Ray Computed
D006573:Heterocyclic Compounds, 1-Ring; D011868:Radioisotopes; D018000:Receptors, Peptide; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; D008187:Lutetium