Can quantifying the extent of ‘high grade’ features help explain prognostic variability in anaplastic astrocytoma?

Abstract

Purpose

Both phenotypic and genotypic variations now underpin glioma classification, thus helping to more accurately guide their clinical management. However, WHO Grade III anaplastic astrocytoma (AA) remains an unpredictable, heterogeneous entity; displaying a variable prognosis, clinical course and treatment response. This study aims to examine whether additional tumour characteristics influence either overall survival (OS) or 3-year survival in AA.

Materials and methods

Data were collected on all newly diagnosed cases of AA between 2003 and 2014, followed up for a minimum of 3 years. Molecular information was obtained from case records and if missing, was re-analysed. Histological slides were independently examined for Ki-67 proliferation index, cellularity and number of mitotic figures. Kaplan–Meier and Cox regression analyses were used to assess OS.

Results

In total, 50 cases were included with a median OS of 14.5 months (range: 1–150 months). Cumulative 3-year survival was 31.5%. Median age was 50 years (range: 24 − 77). Age, IDH1 mutation status, lobar location, oncological therapy and surgical resection were significant independent prognostic indicators for OS. In cases demonstrating an OS ≥ 3 years (n = 15), Ki-67 index, number of mitotic figures and percentage areas of ‘high cellularity’ were significantly reduced, i.e. more characteristic of lower-grade/WHO Grade II glioma.

Conclusions

IDH1 status, age, treatment and location remain the most significant prognostic indicators for patients with AA. However, Ki-67 index, mitotic figures and cellularity may help identify AA cases more likely to survive < 3 years, i.e. AA cases more similar to glioblastoma and those cases more likely to survive > 3 years, i.e. more similar to a low-grade glioma.

Keywords:

• Astrocytoma
• histological
• survival
• prognosis
• glioma

Acknowledgements

This study was presented as a poster presentation at the 23rd Society for NeuroOncology meeting, November 2018, New Orleans, USA and the 2019 Society of British Neurosurgeons annual meeting, March 2019, Manchester, UK.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

This study received no funding.