ABSTRACT
The study of the way cancers free themselves from the constraints of body needs, and of the way they spread, has shed much light on the natural history of this disease. Cells normally exist attached to each other and to the extracellular matrix (see tissues in Chapter 1, p. 15). Blood cells (p. 21), especially white blood cells, are an exception to this rule. Red blood cells (RBCs) are loose but are confined to circulation. They must be free in order that the tissue we call blood behaves as a fluid. White blood cells (WBCs) are completely free to pass through capillary walls into the tissues, and they need this ability in order to fight infection. Inflammation (p. 82) is all about facilitating this freedom of movement for WBCs in and out of tissues during infection.
