In Vivo Succinate Detection After External Beam Radiation Therapy in SDHx- Paragangliomas

Qualitative and quantitative biomarker of response to radiotherapy is needed in paragangliomas. We aim at assessing the added value of 1H-SRM for the evaluation of early response to EBR therapy in patients with cervical SDHx PGL.

Paragangliomas (PGL) are rare neuroendocrine tumors inherited in 40% of cases. SDHx genes (SDHA, SDHB, SDHC, SDHD), encoding the 4 subunits of the mitochondrial enzyme succinate dehydrogenase (SDH), are the most frequently involved. Accumulation of succinate, the substrate for SDH, is a very specific biomarker for these mutations. Recently, we have demonstrated the feasability of detecting and quantifying succinate in tumors in vivo, by magnetic resonance spectroscopy (1H-SRM). Patients carrying these mutations frequently develop cervical PGL for which the treatment of choice is external beam radiation therapy (EBR). The objective of this project is to determine the feasibility of using 1H-SRM for the evaluation of early response to EBR therapy in patients with cervical SDHx PGL.