NIMG-56. CHARACTERISTIC RESPONSE PATTERNS IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA AFTER TREATMENT WITH HIGH SINGLE DOSES OF RADIOTHERAPY

ABSTRACT: Abstract BACKGROUND Healthy brain tissue responses to radiotherapy (pseudoprogression/radiation necrosis) may bias MRI-based tumor response evaluations. To understand these changes specifically after high doses of radiotherapy, we analyzed MRIs of patients of the INTRAGO study, a phase I/II dose-escalation trial on intraoperative radiotherapy in glioblastoma. METHODS Patients enrolled in INTRAGO (NCT02104882) received an intraoperative boost of 20-40 Gy followed by standard adjuvant radiochemotherapy and maintenance chemotherapy. In the present analyses, only patients who received per-protocol therapy and those, who underwent standardized serial MRI follow-ups including DSC-PWI, were included and assessed with special focus on perilesional enhancement pattern, volume, and mean rCBV. Mean leakage-corrected rCBV within enhancing lesions was computed for all MRI follow-ups. RESULTS Overall, 12/15 (80%) patients (median age 60.5 [range 46-73] years) were included in the analysis. Distant failure was the predominant failure pattern (7/12 [58.3%]) leading to salvage therapy after a median follow-up of 372.5 days (range: 72-991 days), while local tumor recurrence was observed in one case (8.3%). On the first follow-up MRI all patients demonstrated perilesional enhancement of varying extent: in 3/12 (25%) patients thin linear, in 1 (8.3%) nodular, in 7 (58.3%) combined linear and nodular, and in 1 (8.3%) voluminous, indistinct, mesh-like. In the course, most patients developed the latter two patterns (8/11 [72.2%]). Three different patterns of enhancing lesion volume were observed: in 3/10 (30%) an early (<200 days) continuous decrease, in 2/10 (20%) a marked early increase, and in 5 (50%) a marked late (?200 days) increase. The overall linear trend in rCBV was negative in most patients (8/11 (72.2%)). CONCLUSIONS High doses to the tumor cavity result in characteristic perilesional enhancement patterns. These results will be useful for the response evaluation of patients exposed to high doses of radiotherapy in future studies, such as the multicenter randomized INTRAGO II trial (NCT02685605).

SUBMITTER: Forster A 

PROVIDER: S-EPMC5693077 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature