Soon after metastasis, the cancer becomes deadly. Thousands of individual cells or microscopic tumors may lie hidden in the body. Every each of them must be hunted down and killed. If just one is left anywhere, it will grow again and again until it finally wins. Having grown, a cancer may take over an artery, blocking the flow of blood to such vital organs as the kidneys, liver and heart. Cancer in the pancreas or the bone marrow may reduce the blood's ability to clot. If internal bleeding begins elsewhere in the body - possibly from a blood vessel ruptured by a metastasized tumor - the victim may die of it. Cancer colonies in the lymphatic system so weaken the body's defenses that an ordinary fungus infection, usually simple and easy to cure, will rage out of control.
Of all cancer's effects, the best known and most disturbing may be a pattern of symptoms called cachexia. It begins with an inexplicable loss of appetite. Weight drops off - sometimes slowly, sometimes with frightening speed - muscles become weak, sleep elusive. Pain is constant. As the malnourished body deteriorates, wastes within it reachtoxic levels. Eventually the victim goes into a deep, terminal coma. Cachexia is seen in patients with cancer, AIDS,chronic obstructive lung disease, congestive heart failure and tuberculosis.
Such are the ravages of advanced cancer, the ultimate effects of a single diseased cell. The disease is both ancient and universal. Examinations of Egyptian mummies have revealed bone cancer in people who lived 5,000 years ago. The Incan Indians who inhabited Peru 24 centuries ago developed not only bone cancer, but a virulent form of skin cancer called melanoma. Among both peoples, the incidence of the disease was apparently low; only a few cancers have been seen in the thousands of mummies and skeletons that have been studied. The ancient egyptians and inca were short-lived peoples; most of them presumably died of other diseases or of injuries long before cancer had time to develop.
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