Cancer

Encyclopedia of Alternative Medicine by Douglas Dupler

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Definition

Cancer is not just one disease, but a large group of almost 100 diseases. It is a genetic disease, with its two main characteristics are uncontrolled growth of the cells in the human body and the ability of these cells to migrate from the original site and spread to distant sites.

Description

One out of every four deaths in the United States is from cancer. It is second only to heart disease as a cause of death in the United States. About 1.2 million Americans are expected to be diagnosed with cancer this year, of which more than 500,000 are diagnosed as terminally ill. Cancer can attack anyone. Since the occurrence of cancer increases as individuals age, most of the cases are seen in adults, middle-aged or older. The most common cancers are skin cancer , lung cancer , colon cancer, breast cancer (in women), and prostate cancer (in men). In addition, cancer of the kidneys, ovaries, uterus, pancreas, bladder, rectum, and blood and lymph node cancer (leukemia and lymphoma) are also included among the 12 major cancers that affect most Americans.

Cancer, by definition, is a disease of the genes. A gene is a small part of DNA, which is the master molecule of the cell. Genes make proteins, which are the ultimate workhorses of the cells. It is these proteins, along with other substances, that allow our bodies to carry out the many processes that permit people to breathe, think, move, etc. Many genes produce proteins that are involved in controlling the processes of cell growth and division. An alteration, or mutation, to the DNA molecule can disrupt the genes and produce faulty proteins. This causes the cell to become abnormal and lose its restraints on growth. The abnormal cell begins to divide uncontrollably and eventually forms a new growth known as a tumor or neoplasm (medical term for cancer meaning "new growth"). In a healthy individual, the immune system can recognize the neoplastic cells and destroy them before they get a chance to divide. However, some mutant cells may escape immune detection and survive to become tumors or cancers.

Tumors are of two types, benign or malignant. A benign tumor is slow growing, does not spread or invade surrounding tissue, and once removed, it does not usually recur. A malignant tumor, on the other hand, invades surrounding tissue and has the capacity to spread to other parts of the body. If the cancer cells have spread to the surrounding tissues, then, even after the primary malignant tumor is removed, it generally recurs either locally or to a distant site. A majority of cancers are caused by changes in the cell's DNA because of damage due to the cell's environment. Environmental factors that are responsible for causing the initial mutation in the DNA are called carcinogens, and there are many types. Some cancers also have a genetic basis. In other words, an individual could inherit faulty DNA from a patient's parents, which could predispose the patient to getting cancer. There is also the two "hit" theory, where there is a combination of a genetic mutation and a stimulation of cell division and/or replication, due to environmental circumstances. While this scientific evidence that both factors (environmental and genetic) play a role, less than 10% of all cancers are purely hereditary. Cancers that are known to have a hereditary link are breast cancer, colon cancer, ovarian cancer , and uterine cancer .

There are several different types of cancers. Carcinomas are cancers that arise in the epithelium (the layers of cells covering the body's surface and lining the internal organs and various glands). Ninety percent of human cancers fall into this category. Melanomas are cancers that originate in the skin, usually in the pigment cells (melanocytes). Sarcomas are cancers of the supporting tissues of the body, such as bone, muscle, and blood vessels. Cancers of the blood and lymph glands are called leukemias and lymphomas respectively. Gliomas are cancers of the nerve tissue.

Causes & symptoms

Causes & risk factors

The major risk factors for cancer are: tobacco, alcohol, diet, sexual and reproductive behavior, infectious agents, family history, occupation, environment, and pollution. According to the estimates of the American Cancer Society (ACS), approximately 40% of the cancer deaths in 1999 were due to tobacco and excessive alcohol use. An additional one-third of the deaths will be related to diet and nutrition. Many of the one million skin cancer cases that are estimated for this year will be due to overexposure to ultraviolet light from the sun's rays. It should be noted that medical science has not been able to pinpoint many of the exact causes of cancer, but has been able to estimate risk factors and occurrence associated with various agents.

Tobacco. Eighty to ninety percent of lung cancer cases occur in smokers. Smoking has also been shown to be a contributory factor in cancers of upper respiratory tract, esophagus, larynx, bladder, pancreas, and probably liver, stomach, and kidney, as well. Recently, scientists have also shown that second-hand smoke (or passive smoking) can increase one's risk of developing cancer. Alcohol. Excessive consumption of alcohol is a risk factor in certain cancers, such as liver cancer. Alcohol, in combination with tobacco, significantly increases the chances that an individual will develop mouth, pharynx, larynx and esophageal cancers. Diet. Thirty five percent of all cancers are estimated to be due to dietary causes. Excessive intake of fat leading to obesity has been associated with cancers of the breast, colon, rectum, pancreas, prostate, gall bladder, ovaries, and uterus. Sexual and reproductive behavior. The human papilloma virus, which is sexually transmitted, has been implicated to cause cancer of the cervix. In addition, it has also been shown that women who have not had children or have children late in life, have an increased risk for both ovarian and breast cancer. Infectious agents. In the last 20 years, scientists have obtained evidence to estimate that 15% of the world's cancer deaths may be traced to viruses, bacteria, or parasites. Family history. Certain cancers like breast, colon, ovarian, and uterine cancer, recur generation after generation in some families. A few cancers, such as the eye cancer "retinoblastoma," a type of colon cancer, and a type of breast cancer known as "early-onset breast cancer," have been shown to be linked to certain genes that can be tracked within a family. It is therefore possible that inheriting particular genes makes a person susceptible to certain cancers.