A healthy cell has a characteristic shape, with a boundary that allows entry to some substances, yet blocks others. Not so the misshapen cancer cell, with its fluid surface and less discriminating boundaries. The cancer cell breaches the controls that hold the cells in place, squeezing into spaces where other cells do not, secreting biochemicals that blast pathways through healthy tissue. The can cer even creates its own personal blood supply. The renegade cell's genetic con trols differ from those of healthy cells and it transmits these differences when it divides. Cancer cells disregard the"rules" of normal cell division that enable the body to develop and maintain distinct organs. To defy that many biological traditions, the cancer cell uses up tremendous amounts of energy, causing further dis-ruptions.