Extent of tumor-brain interface: a new tool to predict evolution of malignant gliomas

Object. Tumor size is one of the features commonly used in oncology to pred ict disease evolution. However, for most primary brain tumors it is not pre dictive of outcome. Taking advantage of a gene therapy trial in which recur rences of glioblastoma were targeted with suicide genes, the authors develo ped a new parameter: the extent of tumor-brain interface- also called surfa ce of tumor volume (STV)- to better describe three-dimensional conformation and the relationship between tumors and the surrounding normal tissue. Cor relations between the STV and the usual clinical parameters were analyzed. Methods. Between 1995 and 1998, 16 patients presenting with recurrent gliob lastomas were enrolled in this study. Preoperative magnetic resonance image s were analyzed on a separate workstation; the interface between tumor and normal brain tissue was measured on each S-mm-thick section to assess STV. The mean STV was 29.2 cm(2), and the mean tumor volume (TV) was 23.8 cm(3). The STV was significantly correlated with survival (Spearman test: r = -0. 54, p = 0.03), but TV was not (Spearman test: r = -0.39, p = 0.15). A separ ate analysis of responding and nonresponding patients showed that, as expec ted, STV was negatively correlated with survival among nonresponding patien ts (p = 0.04), but that among responding patients there was a positive tend ency between STV and survival. Conclusions. These findings indicate that STV may be a useful tool for pred icting the evolution of malignant gli oma. Moreover, in future gene therapy trials in which such in situ approaches are used, increasing density and i m proved distribution of transfer cells should be taken into consideration as an important issue for efficacy.