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Cancer
Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to invade other tissues, either by direct growth into adjacent tissue through invasion or by implantation into distant sites by metastasis. Metastasis is defined as the stage in which cancer cells are transported through the bloodstream or lymphatic system. Cancer may affect people at all ages, but risk tends to increase with age. It is one of the leading causes of death in developed countries.
There are many types of cancer. Severity of symptoms depends on the
site and character of the malignancy and whether there is metastasis. A
definitive diagnosis usually requires the histologic examination of tissue by a pathologist. This tissue is obtained by biopsy or surgery. Most cancers can be treated and some cured, depending on the specific type, location, and stage. Once diagnosed, cancer is usually treated with a combination of surgery, chemotherapy and radiotherapy.
As research develops, treatments are becoming more specific for the
type of cancer pathology. Drugs that target specific cancers already
exist for several cancers. If untreated, cancers may eventually cause
illness and death, though this is not always the case.
The unregulated growth that characterizes cancer is caused by damage to DNA, resulting in mutations to genes that encode for proteins
controlling cell division. Many mutation events may be required to
transform a normal cell into a malignant cell. These mutations can be
caused by chemicals or physical agents called carcinogens,
by close exposure to radioactive materials, or by certain viruses that
can insert their DNA into the human genome. Mutations occur
spontaneously, or are passed down generations as a result of germ line
mutations.
Many forms of cancer are associated with exposure to environmental factors such as tobacco smoke, radiation, alcohol and certain viruses. While some of these can be avoided, there is no known way to entirely avoid the disease, and public health and vaccination programs are also important on a global scale.
It is an approved fact that smoking raises the possibility of contracting cancer ten times more. But the relation between smoking and cancer could not be established through experiments till now because experiments could be done only on animals and animals are not smokers. The connection between smoking and cancer cannot be scientifically approved just because cancer is seen among smokers more than in non-smokers. The smoke exhaled by a smoker contains ten times more Nitrosamines than which does he inhales.
Nitrosamine is the chemical contained in cigarette smoke that causes cancer. So it is evidentthat passive smoking are more affected by nitrosamine than smokers. Mouth and throat cancer is seen more in India than in other countries. In the cause of stomach cancer Japan and Germany are in the forefront. While in America more women are affected by breast cancer Indian women are more affected by cancer of the uterus.
The things that can cause cancer are known as Carcinogens. The period from the time of the first contact with these things to the time of showing the first symptoms is known as latency period.
The latency period can extend from five to forty years. Therefore we cannot rule out cancer if it does not appear a few years after the first contact with he carcinogen. On the other hand even a brief contact with the carcinogen can produce cancer even a long period after wards. To make it more explicit, a co-carcinogen is required to produce cancer in the cells.
Theco-carcinogen acts on the pre-malignant cells. Very little quantity of a poisonous chemical will be enough to turn the cells pre-malignant.The pre-malignant state of the cells continues as such, until co-carcinogen appears. The carcinogen turns the pre-malignant cells cancerous.
It was Sir Percival Pott who first discovered that chemicals could cause Cancer. It was also discovered in 1755 AD that Polycyclid Hydrocarbons Present in Coal tar, Aromatic dyes, Asbestos and the like are carcinogens. This fact has universal approbation today. The sad fact with these Compounds is that long before these were found dangerous, they were being Used as preservatives of food and for artificial coloring of Confectionery.
Among these B. V. O. is a very dangerous material, Comparatively a new comer in the family, which has been widely used as a Preservative in cold drinks.
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