Invasiveness of primary and secondary brain tumors in vitro correlated with clinical results.

One hundred fifty-one tumor fragments were collected in the neurosurgical operating amphitheater immediately after removal. Small tumor fragments were transferred into culture flasks and cultured until a confluent monolayer was formed by the outgrowing cells. Flaps of these cell monolayers were mechanically scraped from the culture flasks and confronted with embryonic chick heart tissue in vitro. The evolution of the confrontations was followed for a week. Histological analysis of the confrontations demonstrated three different morphological patterns of interaction between the heart tissue and the tumor-derived cells: 1) progressive engulfment of the tumor-derived cells by the heart tissue (Type I), 2) survival of both the heart tissue and the tumor-derived cells (Type II), and 3) progressive replacement of the heart tissue by tumor-derived cells (Type III). The replacement of the heart tissue by tumor-derived cells was only observed in cells originating from malignant tumors that were invasive and metastatic in vivo. Thus, invasiveness in confrontation culture is correlated with malignancy in vivo.