Impact of oligodendroglial component in glioblastoma (GBM-O): Is the outcome favourable than glioblastoma?

BACKGROUND: Prognosis of patients with glioblastoma with oligodendroglial component (GBM-O) is not well defined. We report our experience of patients of GBM-O treated at our center.

METHODS: Between January 2007 and August 2013, out of 817 consecutive patients with glioblastoma (GBM), 74 patients with GBM-O were identified in our prospectively maintained database. An experienced neuropathologist revaluated the histopathology of all these 74 patients and the diagnosis of GBM-O was eventually confirmed in 57 patients. Patients were uniformly treated with maximal safe resection followed by focal radiotherapy with concurrent and adjuvant temozolamide (TMZ).

RESULTS: At a median follow up of 16 months, median overall survival (OS) and progression free survival (PFS) of the entire cohort was 23 months and 13 months respectively. Near total excision was performed in 30/57 (52.6%). On univariate analysis, age < 50 years was a significant favourable prognostic factor for OS (p = 0.009) and PFS (p = 0.017), while patients with near total resection had a significantly better PFS (p = 0.017), patients who completed a minimum of 6 cycles of adjuvant TMZ had significantly better OS (p = 0.000) and PFS (p = 0.003). On multivariate analysis, none of the above factors were significant except for patient who had completed a minimum of 6 cycles of TMZ (OS; p = 0.000 & PFS; p = 0.015). A comparative analysis of GBM-O patients with a similarly treated cohort of 105 GBM patients during the same period revealed significantly better median OS in favour of GBM-O (p = 0.01).

CONCLUSIONS: Our experience suggests patients with GBM-O have a more favourable clinical outcome as compared to GBM.