Histopathologic and ultrastructural correlates of tumor growth suppression by high energy shock waves.

High energy shock waves (HESW) are cytotoxic to tumor cells as determined by vital staining and impaired ability of viable cells to form colonies in a clonogenic assay. In addition, direct exposure of tumor nodules to HESW results in suppression of tumor growth rate. In order to identify histopathologic and ultrastructural correlates of these observations, R3327AT-3 prostatic tumor cells were exposed to HESW in vitro and in vivo. Damage to cells in suspension was manifested by fragmentation of cells to form debris. At the ultrastructural level, mitochondria were swollen and contained distorted cristae following exposure of tumor cells to HESW. In vivo exposure of tumor nodules to HESW did not cause a distinct histopathologic or ultrastructural effect that could be qualitatively distinguished from spontaneously occurring cell death. Hemorrhage and necrosis were observed in muscle and fibroadipose tissue adjacent to tumor. The mechanism of HESW-induced cytotoxicity is not clear from our studies. Evidence of damage of normal tissues exposed in vivo and tumor cells in vitro is reflected in histomorphological changes.