Impaired survival in resected glioblastoma multiforme patients treated with early chemoradiation

Background: The best time to initiate concurrent chemoradioation (ChRT) with temozolamide after surgery in glioblastoma multiform (GBM) patients has not been clearly established. Our aim was to investigate whether survival is influenced by the time to ChRT in patients with different types of surgery. Methods: We conducted a retrospective study of all the patients treated in our centre from January 2005 to December 2017, with a histological diagnosed GBM, which underwent surgery and completed concurrent ChRT with temozolamide. The time to ChRT was grouped in 4 quartiles, and early ChRT was defined as happening during the first quartile. Surgery type was divided into resection (R) and biopsy (B). Survival at 12 months (OS12m), median progression free survival (mPFS) and overall survival (mOS) were calculated. Other relevant clinical factors were also analyzed. Results: From a total of 160 patients, 119 who completed ChRT were included. The median time to ChRT was 37 days, (Q1=26, Q2=37, Q3=45); 35 (30%) received early ChRT (≤26 days). Patients who underwent R were 101 (85%) and 18 (15%) B. The mean age was 62y, 94 patients (79%) had PS 0-1, MGMT methylation was positive in 23 (19%). There were no significant differences between groups regarding Age, PS and MGMT status; but more patients treated with B received early ChRT (31% vs 8%). The OS12m was shorter for patients who underwent R and received early vs no-early ChRT (35% vs 73%, p = 0.002). No differences in OS12m were found for B patients (0% vs 18%, p = 0.4) according to time to ChRT. For patients who received early ChRT, the mOS was similar despite surgery type (9.9, 95% CI 9.6 – 11 vs 12.9, 95% CI 6.5 – 19.3, p = 0.8, for R and B, respectively). But for patients who did not receive early ChRT, longer survival was achieved in the R vs B subgroup (16.2, 95%CI 14.1 – 17.8 vs 11.1, 95% CI 4.5 – 17.7, p = 0.024, for R and B, respectively) and resection type remained significant in the multivariate analysis (HR = 1.2, p = 0.02). Conclusions: We have found that patients with GBM who underwent resection had a worse prognosis if they received early chemoradiation (≤ 26 days). No differences were found for biopsied patients. A no-early chemoradation approach for patients who underwent resection may be safe. Prospective studies are encouraged. Legal entity responsible for the study: Hospital de la Santa Creu i Sant Pau. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.