Invasion of human brain tumors in vitro: relationship to clinical evolution.

Embryonic chick heart fragments were confronted in vitro with cells from 26 freshly resected human brain tumors. The tumor-derived cells were scored according to their survival and invasiveness. Four different responses were observed: disintegration of the tumor-derived cells (Type I); survival of cells without progressive engulfing or invasion of the heart fragment (Type II); initial encircling of the heart fragment followed by invasion (Type III); and massive invasion on initial contact (Type IV). Pattern Type III or IV was seen in 11 of 14 preparations derived from malignant tumors, and pattern Type I or II was seen in seven of 10 preparations derived from benign tumors. These results suggested that "classical malignancy," based upon the histological classification and the degree of spread in vivo, correlated with invasiveness in vitro.