331PD - Impact of WHO 2016 update and molecular markers in pleomorphic xanthoastrocytoma

Date 09 September 2017
Event ESMO 2017 Congress
Session CNS tumours
Topics Central Nervous System Malignancies
Pathology/Molecular Biology
Presenter Raees Tonse
Citation Annals of Oncology (2017) 28 (suppl_5): v109-v121. 10.1093/annonc/mdx366
Authors R. Tonse, T. Gupta, E. Sridhar, J. Shastri, A. Jain, N. Bano, R. Jalali
  • Radiation Oncology, Tata Memorial Centre, 400012 - Mumbai/IN

Abstract

Background

There is a relative paucity of data regarding outcomes of pleomorphic xanthoastrocytomas (PXA) particularly with respect to the impact of emerging molecular markers. We present our institutional experience of PXA and correlate their outcomes with various clinical and pathological factors.

Methods

Between 2006 to 2016, 37 patients with histologically verified PXA form the study cohort. All patients underwent maximal safe resection; those who had good resection, low MIB-1 index and young age were observed. Adjuvant radiotherapy was given in patients with atypical features on histology, high MIB-1 index and recurrence after first surgery or with significant residual disease. Patients diagnosed with anaplastic PXA were managed by multi-modality approach comprising maximal safe resection, radiotherapy and systemic therapy. BRAFV600E mutation testing was attempted in all 37 paraffin embedded tissue blocks. Progression free survival (PFS) and overall survival (OS) and potential prognostic factors affecting outcomes were analyzed.

Results

Median age at diagnosis was 20 years (range 4–45). Tumors were predominantly in the temporal lobe and seizures were the most frequent symptom at presentation. Gross total resection (GTR) was achieved in 23 cases (62%), a subtotal resection (STR) in 13 cases (35%) and biopsy in one patient. At a median follow-up of 33 months, 3-year and 5-year OS was 80.2% & 74% respectively. Patients who underwent GTR had a better PFS as compared to those who underwent STR (3-year estimates 85.6% vs. 32.3%; p = 0.001). 10 patients (27%) were classified as having anaplastic PXA. PFS was significantly superior in PXA grade II as compared to the anaplastic PXA group (3-year estimates 80.2% vs. 32%; p = 0.007). Of the 27 patients where BRAF V600E testing was successful, 13 patients showed a mutation (48%). 3-year PFS & OS survival in BRAFV600E mutated patients was 51.9% & 76.9% compared to 73% & 75% in BRAFV600E non-mutated patients, respectively. No patient had an IDH1 mutation.

Conclusions

Anaplastic PXA has worse outcomes as compared to PXA grade II. This data may provide valuable insights and set as a benchmark for imparting targeted therapies.

Clinical trial identification

Legal entity responsible for the study

Nil

Funding

Brain Tumour Foundation of India

Disclosure

All authors have declared no conflicts of interest.