Tumor necrosis and cell detachment.

Cell detachment from and around Walker 256 tumors grown in rats is quantitated by a standardized in vitro shaking procedure. The volume of cells detached from cancers of similar size is virtually the same in tumors growing in the liver, the spleen, in intramuscular and in subcutaneous sites. In cystic tumors, greater volumes are detached from the innermost regions of the walls adjacent to necrotic material than from the outermost parts. More liver perenchymal cells are shaken free of liver adjacent to a tumor interface than from regions 0.5 and 1.0 cm distant from it. Detachment of tumor and liver cells is also enhanced by prior incubation of tissue samples with necrotic extracts. It is suggested that the necrotic regions of tumors, and products derived from them, facilitate the detachment of tumor cells and cells composing the normal tissues surrounding them, thereby potentially promoting metastasis and invasion.