Stereological estimates of nuclear volume and other quantitative variables in supratentorial brain tumors : practical technique and use in prognostic evaluation

The use of morphometry and modern stereology in malignancy grading of brain tumors is only poorly investigated. The aim of this study was to present these quantitative methods. A retrospective feasibility study of 46 patients with supratentorial brain tumors was carried out to demonstrate the practical technique. The continuous variables were correlated with the subjective, qualitative WHO classification of brain tumors, and the prognostic value of the parameters was assessed. Well differentiated astrocytomas (n = 14) had smaller estimates of the volume-weighted mean nuclear volume and mean nuclear profile area, than those of anaplastic astrocytomas (n = 13)(2p = 3.1 · 10−3 and 2p = 4.8 · 10−3, respectively). No differences were seen between the latter type of tumor and glioblastomas (n = 19). The nuclear index was of the same magnitude in all three tumor types, whereas the mitotic index was significantly increased in glioblastomas (2p = 0.01). Three-dimensional, shape-independent estimates of macroscopical tumor volume were not different in anaplastic astrocytomas and glioblastomas (2p = 0.39). Histological type of tumor and mitotic index were of significant prognostic value (2p = 8.2 · 10−6 and 2p ≈ 0.05, respectively). Age above the median and short duration of symptoms were significantly associated with short survival (2p = 0.01). Further investigations of larger series of patients are needed to define the clinical usefulness of these objective, reproducible, and quantitative techniques in the prognostic evaluation of primary brain tumors.