INTRODUCTION
In the American society, cancer is the disease most feared by the majority of people
within the U.S. Cancer has been known and described throughout history.
In the early 1990s nearly 6 million cancer cases and more than 4 million deaths have
been reported worldwide, every year. The most fatal cancer in the world is lung cancer,
which has grown drastically since the spread of cigarette smoking in growing countries.
Stomach cancer is the second leading form of cancer in men, after lung cancer. Another
on the increase, for women, is breast cancer, particularly in China and Japan. The
fourth on the list is colon and rectum cancer, which occurs mostly in older people.
In the United States more than one-fifth of the deaths in the early '90s was caused by
cancer, only the cardiovascular diseases accounted at a higher percentage. In 1993 the
American Cancer Society predicted that about 33% of Americans will eventually get cancer.
In the United States skin cancer is the most dominating in both men and women, followed
by prostate cancer in men and breast cancer in women. Yet lung cancer causes the most
deaths in men and women. Leukemia, or cancer of the blood, is the most common type in
children. An increasing incidence has been clearly observable over the past few decades,
due in part to improved cancer screening programs, and also to the increasing number of
older persons in the population, and also to the large number of tabacco
smokers--particularly in women. Some researchers have estimated that if Americans
stopped smoking, lung cancer deaths could virtually be eliminated within 20 years.
The U.S. government and private organizations spent about $1.2 billion annual for cancer
research. With the development of new drugs and treatments, the number of deaths among
cancer patients under 30 years of age is decreasing, even though the number of deaths
from cancer is growing overall.
TYPES OF CANCER
1.Cancer is the common term used to designate the mosst aggressive and usually fatal
forms of a larger class of the diseases known as neoplasms. A neoplasm is described as
being relatively autonomous because it does not fully obey the biological mechanisms that
govern the growth and the metabolism of individual cells and the overall cell
interactions of the living organism. Some neoplasms grow more rapidly than the tissues
from which they arise, others grow at a normal pace but because of the other factors
eventually become recognizable as an abnormal growth and not normal tissue. The changes
seen in neoplasm are heritable in that these characteristics are passed on from each cell
to ots offspring, or daughter cells. Neoplasm occurs only in muticellular organisms.
The main classification of the neoplasms as either benign or malignant relates to their
behavior. Several relative differences classify these two classes. A benign neoplasm,
for instance, is harmless, but malignant is not. Malignancies grow more rapidly than do
benign forms and invade adjacent normal tissues. Tissue of a benign tumor is structured
in a manner similar to that of the tissue from which it is derived, malignant tissue,
however, has an abnormal and unstructured appearance. Most malignant tumors, in fact,
exhibit abnormalities in chromosome structure, that is, the structure of the DNA
molecules that constitute the genetic materials duplicated and passed on to later
generations of cells. Most important, however, benign neoplasms do not begin to grow at
sites other than the point of origin, whereas malignant tumors do. The term TUMOR is
used to indicate a readily defined mass of tissue that is recognizable from normal living
tissue. Thus a scar, an abcess , and a healing bone callus are all designated as tumors,
but they are not neoplasms.
Besides being classified according to their behavior, neoplasms can also be classified
according to the tissue from which they arose, and they are usually designated by a
tissue-type prefix. A general system of tnonmenclature has als arisen to distinguish
benign and malignant neoplasms. The designation of the benign neoplasm usually is
signified by the suffix-oma added to the appropriate tissue type prefix. Malignant
neoplasms are separated into two general classes. Cancers arising from such supportive
tissues as muscle, bone and fat are termed sarcomas. Cancers arising from such
epithelial tissues as the skin and lining the mouth, stomach, bowel, or bladder are
classified as carcinomas. Examples of benign neoplasms are a lipoma (from fat tissue)
and an osteoma (from bone). Malignant counterparts of these neoplasms are a liposrcoma
and an osteosarcoma. The term adenoma is used to indicate a benign neoplasm of glandular
tissue, and corresponding malignancies are termed adenocarcinomas.
Exceptions to this form of nomenclature include thymomas, which are either malignant or
bengnneoplasms of the thymus gland, and such descriptive terms os dermoid, a benign tumor
of the ovary. The suffix-blatoma denotes a primitive, usually malignant, neoplasm.
Leukemia, literally meaning "white blood," is the term used to designate malignant
neoplasms having a major portion of their cells circulating in the blood stream. Most
leukemia's arise in the blood-forming tissues, such as the bone and in the lymphatic
tissues of the body.
CAUSES OF CANCER
2.A cancer-causing agent-- chemical, biological, or physical--is termed a carcinogen.
Substances are labeled carcinogens if, when administered to a population of previously
untreated organisms, thet cause a statistically significant increase in the incidence of
the neoplasms compared with the incidence in subjects that are left untreated.
FOOTNOTES
1.) ACADEMIC AMERICAN ENCYCLOPEDIA (pp. 5-10)
2.)AMERICAN CANCER SOCIETY'S COMPLETE BOOK OF CANCER (25-27)
BIBLIOGRAPHY
AMERICAN CANCER SOCIETY'S COMPLETE BOOK OF CANCER, GROLIER ELECTRONIC PUBLISHING COMPANY
ANDERSON, PAUL, ADVANCES IN CANCER CONTROL, GROLIER ELECTRONIC PUBLISHING COMPANY
LASZLO, JOHN, UNDERSTANDING CANCER, GROLIER ELECTRONNIC PUBLISHING COMPANY
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