ESMO Congress 2024 | OncologyPRO

Abstract 1152P

Background

Somatostatin-receptor (SSTR)-targeted-PET/CT is widely used for diagnosis and disease monitoring of pheochromocytoma / paraganglioma (PPGLs). The aim of this study was to assess the potential of the novel SSTR-targeted tracer [18F]-SiTATE in diagnosing PPGLs by comparing imaging parameters to tumor marker levels and secretory activity in a small cohort of patients diagnosed with this rare tumor type.

Methods

All patients with histologically confirmed PPGL presenting for [18F]-SiTATE-PET/CT at LMU Klinikum between 10/2020 and 02/2024 as well as hormonal laboratory analysis of both plasma and 24-hour urine samples within up to 100 days were included. Metabolic tumor volume (MTV) was assessed using a threshold of mean standard uptake value (SUVmean) of 5.0. Total lesion uptake (TLU) was assessed with SUVmean x MTV. Correlation was tested using spearmanś rank correlation test.

Results

34/39 patients (median age: 55, range: 5-83) were included in this study. 5 patients with cervical PGL were excluded. 21 patients had metastatic disease. There was a moderate correlation between TLU and MTV and urinary dopamine (r=0.50-0.51, p<0.05) as well as norepinephrine (r=0.50-0.54, p<0.05). TLU and MTV correlated moderately with serum chromogranin-A levels (r= 0.60, p<0.01, respectively). A moderate correlation was determined between TLU and MTV with plasma normetaphrine and 3-Methoxytyramine (r=0.52-0.56, p<0.01).

Conclusions

MTV and TLU measured with [18F]-SiTATE-PET/CT correlate well with the tumor marker chromogranin-A in serum and with particular biomarkers of the catecholamine pathway in urine and plasma, reflecting metabolic tumor activity. Within the limits imposed by the relatively small cohort, our results suggest that TLU in [18F]-SiTATE-PET/CT could be used as imaging biomarker for monitoring of disease progression and secretory activity in patients with PPGL.