The role of stereotactic conformal radiation boost in the temozolomide-based chemoradiation for glioblastoma multiforme: Preliminary analysis

Abstract

12513 Background: Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. Aim of this analysis was to evaluate tolerance and outcome of the dose intensification by stereotactic conformal radiotherapy (SCRT) and concomitant chemotherapy with temozolomide Methods: From October 2003 to April 2006, 58 patients (34 males, 58.6%, 24 females, 41.4%) with histological diagnosis of glioblastoma multiforme received postoperative radiochemotherapy with SCRT boost. Median age was 58 yrs. ( range 25–80 yrs.). Twenty-nine out of 58 patients (50%) received a total dose of 70 Gy by conformal radiotherapy and SCRT boost delivered as concomitant and sequential, or sequential alone. The remainig 29 patients (50%) received a standard of 5940 cGy (180 cGy/day; CTV3: tumor bed + residual tumor if present + oedema; CTV2: tumor bed + residual tumor if present + 1.5 cm margins. CTV1: tumor bed + residual tumor if present + 0.5 cm margins only for the SCRT group). All patients received concomitant Temozolomide, 75 mg/m2 for a median duration of 28 days (range 14–45, depending on the chemoradiation schedule), and adjuvant chemotherapy with temozolomide for 6 cycles or until disease progression. Toxicity was recorded according to RTOG criteria; Survival analysis was calculated by the Kaplan-Mayer method and log-rank testing was used for groups comparison. Results: A 100% compliance was observed in both the groups of patients. A grade 3–4 acute neurological toxicity was registered in two patients treated with SCRT compared to one patient in the group which did not receive SCRT. One case of radionecrosis was observed in the SCRT group; in no case of either group neurological worsening nor corticosteroidal dependence were registered. At a median follow-up of 19 months (range 4–39), a trend towards a better outcome was observed in patients treated with SCRT, since the 1-year OS was 85.9% for SCRT patients (median not achieved) compared to 68.7% for the remaining patients (p=0.07). Conclusion: Our preliminary analysis suggests that a higher dose of RT delivered by conformal stereotactic boost did not increase acute or late toxicity and could achieve a better outcome in patients affected by GBM No significant financial relationships to disclose.