Showing posts with label Epidemiological studies. Show all posts
Showing posts with label Epidemiological studies. Show all posts

Thursday, May 9, 2013

Causes of cancer

DNA and Cancer
In search for the culpable... This search begins since the appearance of this tumoral disease. Francis W. Peabody says that the disease in a human is never the same as the disease in an animal, because since its beginnings every disease affects and also in the same time is affected by that, which we call the emotive life.   

Studies done to discover the origin and the causes of tumors follow two main directions.

1. Epidemiological studies

This studies aim to make evident the characteristics of spreading of cancers and the frequency of this disease in humans. It is their objective to discover the causes of the observed characteristics. This studies in time have discovered a series of social, environmental and genetic factors that are responsible for the frequent appearance of tumors in specific territories and communities.

2. Experimental studies

The experimental study of tumors has as an objective to prove or disprove the cancerous effects of different agents, such as chemicals, viruses, hormones, radiation etc, through artificial production of tumors in experimental animals.

Epidemiologic and experimental studies are strongly intertwined with each other.

Nowadays has been definitely proven that cancers are not caused by a single factor. There exist approximately 200 forms of cancerous diseases and the cancer research continues at full pace. 

Even though a lot of 'the culpables' for cancer have been discovered there are still a considerable amount of cancers with still unknown or doubted origin. Below I will give you a list of accepted and proved agents, responsible in the development of cancer.

1. Chemicals

According to some authors 80-90% of all malign tumors in humans are caused by a reaction of different chemical substances. 

1.1. Polycyclic hydrocarbures 
They are produced as a result of burning in high degrees of any organic substance, such as oil, cobbles, including tobacco and meat products. 

1.2. Azoic Dyes 
They are a group of chemical substances known by this name because of the nitrogen found in their molecules and strong colorant  characteristics, even in the most diluted form.

1.3. Aromatic amines
In particular, cancer risk in humans resulting from exposure to aromatic amines from occupational sources and tobacco smoking is assessed with reference to ecologic, cohort, and case-control studies.

1.4. Alkyls
Among the most important representans of this group we can mention nitrosamines and carbamate. 

1.5. Inorganic chemical substances
The most important ones to be avoided are arsenic, asbestos, chrome, nickel and beryllium.

2. Special chemical substances

Aflatoxins. 

3. Tobacco smoke

Heart and lungs suffer the most. 

3.1. Nicotine
3.2. Carbon Monoxide
3.3. Irritant substances
3.4. Radioactive substances

4. Alcohol 

5. Food Products and the way of eating  

6. Physical Agents

6.1. Radiation
6.2. Mechanical traumas
6.3.Repetitive burns

7. Infective Agents

7.1. Viruses
7.2. Parasites

8. Hormones

9. Hereditiy

10. Psychic factors

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