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Cancer Mechanisms Excerpt from Rachel’s Environment & Health Weekly #418 Cancer is uncontrolled growth of cells. Normal, healthy cells grow by dividing; one cell divides and becomes 2 cells; those 2 divide and become 4 cells, and so on. Cell division is normal. When a cell divides, its genetic molecules (called DNA, or deoxyribonucleic acid) are reproduced in its descendants, the new cells. The genetic molecules (the DNA) contain complete instructions telling the new cells how to function, how to behave, including how (and how fast) to divide. Normal DNA also contains instructions telling cells when to stop dividing. Normal cell division always stops at some point, by natural means; none of us continues to grow forever. When cells fail to stop dividing, they can continue to grow until they kill their host (the person whose body contains the runaway cells). This is cancer. Cancer is now thought to be a genetic disease, or, more properly, about 100 different genetic diseases. According to current medical theory, a cancer tumor develops in stages, starting from a single cell. As a cell accumulates a series of "genetic lesions", a full-blown cancer can begin. A lesion is an injury or loss of functions. Genetic lesions are lesions that occur in the DNA molecules that control a cell’s proper operation, including the accuracy and appropriate rate of cell division. Genetic lesions in a cell can occur at any age, including the time when a fetus is forming in its mother’s womb. Some genetic lesions can be inherited from parents. In other words, some people start life with DNA that has been damaged in some way. Such inherited lesions are present in the fertilized human egg, the single cell from which the new person will grow. Since every cell in a person’s body is descended from that first cell (the fertilized egg), the inherited DNA lesion is present in every cell in the new person’s body. In contrast to an inherited lesion, which affects every cell, a person can also develop a genetic lesion during childhood or as an adult. Such a lesion affects the single cell that first acquired the damage (from exposure to ionizing radiation, or certain chemicals, for example); it will also affect any cells that are descendants of that particular cell, but it will not affect unrelated cells in the body. Cancer is thought to develop after a cell has accumulated several cancer-causing lesions. Medical authorities commonly estimate that 4 to 10 lesions in a cell’s DNA are necessary before a cancer can develop. Some of these lesions may be inherited, and others may be acquired at any age after conception. If this theory is correct, the vast majority of people are not "destined" to get cancer; even though they may inherit a cancer-causing genetic lesion from one of their parents. If they are prudent and avoid unnecessary exposure to carcinogenic materials (such as radiation and certain chemicals) and eat a healthy diet rich in anti-cancer foods (such as dark green and yellow/orange vegetables), they can reduce their chances of developing a tumor. A few people inherit powerful genetic lesions that confer a high chance of getting cancer in a specific organ, with the cancer often occurring at a young age. Such powerful inherited lesions seem to account for 5 to 10 percent of all human cancers. Even these powerful inherited lesions may need additional lesions before they can turn into a cancer. The relationship of inherited lesions, and lesions that develop later, are poorly understood. It may turn out that cancer never develops without an inherited "head start" and almost always requires the interaction of an inherited lesion with other forces. The "other forces" would be pesticides or pesticide by-products, carcinogens in the diet, certain industrial chemicals, inadequate exercise, EMF’s (electromagnetic fields), ionizing radiation, and so on. This theory of cancer implies that a large proportion of all cancers can be avoided or eliminated if we correctly identify and eliminate the non-inherited forces which act alone, or act along with inherited lesions, to produce cancer. The rates of incidence (occurrence) of 19 kinds of cancer are increasing in the US, and the death rates of 12 kinds of cancer are increasing. (See Rachel’s Environment & health Weekly #417). (Those cancers for which incidence rates are rising and death rates are falling are the cancers we are "learning to live with." They are: cancers of the colon/rectum; larynx; testicles; bladder; Hodgkin’s disease; childhood cancers; leukemia; and thyroid. People are surviving these cancers because of surgery, chemotherapy, and radiation treatments. Although it is good news that more people are surviving these cancers, it is hard to argue that this is an unqualified medical success because the quality of life for cancer survivors, and their families is often wretched.) Among the most rapidly-increasing and preventable cancers is breast cancer. In the US, about 182,000 new cases of breast cancer will be reported in 1994 (1000 in men, 181,000 in women); and about 50,000 American women now die each year from beast cancer.
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