Cancer had been such a dark and fearful mystery because it takes so many forms. It can strike any organ, any tissue, anywhere in the body. Despite this diversity, all cancers share certain characteristic. They are all diseases of individual cells, the basic building blocks of plants and animals. No multicelled organism is immune to these diseases. A growth called crown gall, which appears on a number of plants, including daisies and tomatoes, exhibits certain characteristic of cancer. Insects get cancer; the fruit fly, a favourite creature of experimenters because it reproduces so rapidly - more than 35 generations per year - suffers from both brain tumors and blood cancers. Fish that swim through harbors polluted by tars and oil that cause cancer in human being develop cancers similar to human cancer. Dogs, cats, cows and horses get cancers of various types. Some wild animals such as cheetahs and certain asiatic bears, were once thought to be immune. They are not. Protected in a laboratory or a zoo from disease and their natural enemies, so that they consistently reach an age old for their species, they too develop the disease.

In all of these living thing, a cancer starts when something goes awry inside a cell, the smallest unit of living tissue. An error is somehow introduced into the genetic code, the complex pattern of molecules that normally ensures the reproduction of a new cell perfectly fitted to its function in the body. The genetic error may be caused by a chemical; by radiation therapy; or by the tiny agent of disease called virus. In addition, many genetic disruptions are simply random slippages of the cell's machinery, with no discernible cause. The result is the same : a new born freak cell called a mutant.
Few mutant cells survive long enough to do any damage. Some are so deformed or deficient that they wither and die; others are destroyed by the body's natural defenses. In a cancer victim - however - at least one such cell hangs on to life and eludes the body's defender. The cell divided into two, the two into four. Eventually, a billion or more may form a tumor, a swollen lump perceptible to the touch.

Rarely do swellings indicate the growth of new tissue and even more rarely are they dangerous. The hard knot that follows a bump on the head is simply an accumulation of fluid beneath the skin; other swellings are caused by pus at the site of an infection. Even a tumor consisting of mutant cells is seldom cancerous; most tumorous lumps are classified as benign and generally can be ignored. Only malignant or cancerous, tumors inevitably pose a thread to life.

Continue to "How Malignancy Begins (part 2)"
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