177Lu-labeled somatostatin receptor targeted radionuclide therapy dosimetry in meningioma: a systematic review.

Introduction: Few therapeutic options are currently available for refractory meningiomas. Encouraging results have been reported for ¹⁷⁷Lu-labeled somatostatin receptor-targeted radiopeptide therapy (SSTR-RT). The current therapeutic scheme is based on the fixed doses that are recommended for neuroendocrine tumor treatment. However, in personalized medicine, tumor dosimetry can be determined from repeat ¹⁷⁷Lu scintigraphy. The aim of this review was to report on the methods used for calculating the tumor absorbed dose (AD) in meningioma patients treated with ¹⁷⁷Lu-SSTR-RT and their values.

Evidence acquisition: The search was performed in Medline, Embase and the Cochrane Library until March 1^st, 2024 to retrieve papers related to the topic. The following terms were used for searching: (meningioma) AND ((sstr) OR (receptors somatostatin) OR (somatostatin) OR (octreotide)) AND ((PRRT) OR (radionuclide therapy) OR (dotatate) OR (dotatoc) OR (177Lu-DOTATOC) OR (177Lu-DOTATATE) OR (radiopeptide)).

Evidence synthesis: Seven articles (including 46 patients and 108 cycles of treatment) reporting on tumor AD during ¹⁷⁷Lu-SSTR-RT were included in the analysis. The methods of acquisition, reconstruction parameters and postimage processing to determine tumor AD were very heterogeneous among the studies. The meningioma AD associated with the agonist ¹⁷⁷Lu-SSTR-RT reported in the majority of studies ranged from 0.1-1.5 Gy/GBq, which was lower than that reported for neuroendocrine tumors (1.3-22.9 Gy/GBq).

Conclusions: The tumor AD that was reported during treatment with ¹⁷⁷Lu-SSTR-RT in refractory meningioma patients is generally low. Harmonization of the methodology for dosimetry calculations is needed to compare the different reported values and optimize treatment at the individual level.