FET-PET assessed recurrence pattern after radio-chemotherapy in newly diagnosed patients with glioblastoma is influenced by MGMT methylation status

Abstract Background and purpose The aim of the present study was to evaluate factors predicting the recurrence pattern determined by [ 18 F]FET-PET imaging in patients with newly diagnosed glioblastoma after combined radio-chemotherapy treated according to the EORTC/NCIC trial. Material and methods Seventy-nine patients with newly diagnosed GBM treated with radiotherapy plus temozolomide (75mg/m 2 /d) followed by adjuvant cyclic (5/28days) temozolomide (150–200mg/m 2 ) were retrospectively analysed. Recurrence patterns were assessed by means of positron-emission-tomography with [ 18 F]FET and additional MRI; in 54 patients MGMT methylation status was evaluated. Results Whilst 49.4% of the patients had an in-field recurrence, 12.6% an ex-field recurrence and 3.8% a recurrence at the field margin, 34.2% of the patients did not relapse during follow-up (median 595days). Considering all patients included in this study, 41.5% (12/29) of the MGMT methylated population had no relapse, 37.9% (11/29) had an in-field-recurrence and 20.7% (6/29) an ex-field/marginal recurrence, whilst 28.0% (7/25) of the MGMT unmethylated population had no relapse, 64.0% (16/25) had an in-field-recurrence and 8.0% (2/25) an ex-field/marginal recurrence ( p =0.15). Conclusions After the administration of temozolomide concomitant with and adjuvant to radiotherapy in patients with glioblastoma, the pattern determined by [ 18 F]FET-PET seems to be associated with MGMT methylation status.