Glioblastoma: patterns of recurrence and efficacy of salvage treatments.

BACKGROUND It is controversial if distant recurrence of glioblastoma is more common after temozolomide (TMZ) concurrent with radiotherapy (RT). Optimal therapy for patients with recurrent disease after RT/TMZ is unclear. Our purpose was to evaluate recurrence patterns in glioblastoma and the effect of treatment at recurrence upon survival. METHODS We performed a retrospective review of 67 patients with newly diagnosed glioblastoma treated with RT/TMZ between 2003-2007. Statistical analyses included Kaplan-Meier method for survival, and multivariate Cox proportional hazards model for the effect of salvage treatment on survival. RESULTS 58 patients (86.6%) recurred locally; 9 patients (13.4%) had a distant non-contiguous focus of new disease. Median survival(MS) was 17 months; median time-to-progression(TTP) 6.8 months. The local and distant groups had comparable prognostic factors. There was no difference in MS(p=0.35) or TTP(p=0.95) by location of recurrence. At relapse, 26 patients(38.8%) received continuous, dose-intense TMZ, 24(35.8%) other therapy(4.5% RT; 20.9% lomustine+/-procarbazine; 4.5% etoposide; 1.5% conventional TMZ; 4.5% TMZ then lomustine), and 17(25.4%) were untreated. Dose-intense TMZ was associated with prolonged MS compared to all other patients(21.5 months vs. 12.4 months, p=0.019, HR=3.86, 95%CI: 1.81-8.22) and similar to MS with other chemotherapy regimens(18.8 months, p=0.40, HR=1.30, 95% CI: 0.65-2.61). CONCLUSION The pattern of recurrence of glioblastoma treated with RT/TMZ was predominantly local. Second-line treatment with continuous dose-intense TMZ may prolong survival in patients with recurrent glioblastoma. Overall survival is similar to other conventional salvage regimens; however TMZ may be better tolerated. This study is limited by its retrospective nature and potential selection bias. Prospective controlled studies are needed.