Relationship between histopathology and in vitro clonogenicity in breast cancer

The human tumor clonogenic assay was used to culture 268 primary and metastatic breast cancer samples. Cultures of 181 specimens were prepared in the double-layer agar system and 87 in a modified system utilizing a liquid upper layer. Successful growth (greater than 5 colonies) was 53% for the agar 2-layer method and 68% for the modified system. Three morphologically distinct colony types were observed: Type I--small, dark, compact colonies; Type II--clear colonies; and Type III--mixed colonies of Types I and II. In 73 cases the histologic slides of the original tumor specimens were reviewed, and the histopathological findings correlated with the clonogenicity of the specimens. There was a significant positive relationship between the degree of differentiation and focal microscopic tumor necrosis in the original specimen and its subsequent clonogenicity. However, other histologic parameters did not show any relationship with clonogenicity.