“Role of 18-Fet in high grade gliomas re-irradiation: from detection of disease recurrence to a predictive value"

Most high-grade gliomas (HGGs) recur after initial multimodal therapy and re-irradiation (Re-RT) has been shown to be a valuable re-treatment option in selected patients. MRI is the gold standard for diagnosis and treatment planning of HGGs, but has some limits to differentiate between some lesions that can occur after treatments and the recurrence. 18F-fluoroethyl-tyrosine (FET) has been proven to be able to non-invasively differentiate treatment-related changes from real tumor progression and could also have a predictive potential in response of treatment. The presence of hypoxic cells in high-grade glioma (HGG) is one of the main reasons of local failure after radiotherapy (RT). The use of hyperbaric oxygen therapy (HBO) could help to overcome the problem of hypoxia in poorly oxygenated regions of the tumor. HBO-RT is a pilot trial to evaluate the efficacy of hypofractionated image-guided helical TomoTherapy (HT) after HBO in the treatment of recurrent HGGs. In a group of patients enrolled in HBO-RT trial FET was acquired before and after treatment and we performed a retrospective analysis to evaluate the ability of FET to discriminate between HGGs recurrence and treatment-related changes (TRC) and the predictive potential of FET acquired before hyperbaric re-irradiation of recurrent high-grade gliomas along with other imaging and clinical parameters.