Prognostic Value of Histological Features in Diffuse Astrocytomas WHO Grade II

The histopathological diagnosis of diffuse astrocytoma is challenging. As the WHO classification system is based on subjective assessments, the prognosis for the individual patient is somewhat uncertain. The aim of this study was therefore to investigate the prognostic value of various histological features, Ki-67/MIB-1 labeling index (LI), and clinical factors. The study was designed as a retrospective study of 109 patients consecutively operated for their primary diffuse astrocytoma WHO grade II. Clinical data was collected from patient files. All routine stained sections were revised, and 20 different histological features were recorded, including cell density, atypia, mitoses, apoptoses, secondary structures (of Scherer), microcysts, and lymphocytic infiltration. Ki-67/MIB-1 LI was determined by conventional immunohistochemistry. Using uni- and multivariate analyses, the prognostic value of these factors was assessed as well as clinical parameters. Median age at primary surgery was 40 years (range 18-75). The median overall survival was 70 months with a minimum follow-up of 3 months. Neither histopathological features nor Ki-67/ MIB-1 LI (median value of 4.5% (range 0.1-16%) indicated unfavorable prognosis. However, age > 40 years, gender (male), poor preoperative performance score, and biopsy rather than resection were significant negative prognostic factors in both uni- and multivariate analyses. Among diffuse grade II astrocytomas neither any histopathological trait nor Ki-67/MIB-1 LI achieved prognostic significance, whereas clinical parameters were shown to serve as the major prognostic factors for these patients.