Analysis of dosimetry and clinical variables in treatments of neuroendocrine tumours with [177Lu]Lu-DOTA-TATE.

Abstract

Purpose: The main objectives were to study differences between the first and the fourth cycle in dosimetry variables in patients treated for neuroendocrine tumours with four cycles of [¹⁷⁷Lu]Lu-DOTA-TATE, as well as to look for absorbed dose-effect correlations aiming to help individualise and optimise this therapy for future patients.

Material and methods: SPECT based dosimetry of tumour lesions and kidneys was performed in the first and the fourth cycles of the [¹⁷⁷Lu]Lu-DOTA-TATE treatments for 17 patients from 2020 to 2023. Clinical variables of interest were collected in order to look for correlations with some dosimetry variables. Statistical analysis was performed using the R software.

Results: Regarding dosimetry variables, for lesions a significant decrease in absorbed dose, mass and initial activity between the first and fourth cycles was observed. For kidneys, a significant increase in absorbed dose was observed. Effective decay constants did not significantly change neither for lesions nor for kidneys. The relative decrease in lesion masses correlated with their total absorbed dose. Total absorbed doses to kidneys were well below the toxicity limits mostly used in this therapy. Relative decrease in lesion absorbed doses was significantly lower for tumour primary sites in ileum and jejunum compared to those in pancreas. Moreover, radiological response correlated with clinical response.

Conclusions: The results seem to indicate that the current treatment scheme could be optimised in order to obtain better treatment outcomes.