Added: 02/09/2006 |
Modern Science and the Understanding of Carcinogenesis MechanismsCarcinogenesis is a sequential process of transformation of normal cells into malignant ones caused by different factors: exogenous factors (environmental conditions and lifestyle) and endogenous factors (genetic, hormonal, immune factors) and their interaction. The stage development is also caused by exogenous and the influence of endogenous factors. These factors may promote or counteract this process.
Influence of carcinogenesis mechanisms are characterized by external dose i.e. substance concentration in environment or by internal dose i.e. substance concentration is internal environment (blood, urine, tissues, etc) or by biologically effective dose.
Carcinogenesis mechanisms are divided into the following stages:
- Mutations;
- Selective growth of clone;
- Selection of the cells;
- Autonomy of mutated cells;
- Invasion and metastasis.
Carcinogenesis mechanisms also may be stimulated by such factors as foreign objects, alcohol, smoking, chronic inflammations, radiation, pollutants, etc. Sometimes these factors are called carcinogen, or carcinogenic substance i.e. the substances that cause malignant cells creation and development. Birth genetic defects, viral infections and carcinogenesis are also closely related.
Today the science considers carcinogenesis mechanisms as a disorder of normal level of natural mutations i.e. the level when malignant cells are not created.
Carcinogenesis mechanisms need certain period of time. For example, the cancer of lungs of nonsmokers caused by asbestos usually develops not earlier than after 25-40 years. And the cancer of smokers needs 15 or more years of permanent contact with carcinogen to develop. And when the patient stops his contact with the substance the risk of tumor development is reduced.
Any contact with carcinogens is more dangerous for younger people and carcinogenesis mechanisms need less time in this case.
In recent years; cancer molecular biology has made great gains in research and application. It has studied and described many carcinogens and oncogenes, their activation and deactivation in carcinogenesis, their influence on genetic changes in organism, mutations and other damages.
For example, there are several genes which mutation causes hereditary cancer forms, e.g. it is retinoblastoma, which mutation causes hereditary retinoblastoma, or gene P53, which mutation causes hereditary breast cancer, and others.
Today the science says that unfavorable phenotype occurs in 30-50 per cent and the chance that this phenotype causes cancer is very low (5-10 per cent).
In future modern molecular biology achievements will allow influencing carcinogenesis mechanisms and defining carcinogens influence on the base of individual sensibility of each organism.
The question of how to avoid any contact with carcinogens is unfortunately, impossible to accurately answer. Even recommended fruits and vegetables consist of some volume of carcinogens. Each person should minimize his contact with ultraviolet irradiation and ionizing radiation. Especially it concerns blond, red-haired, blue-eyed and freckled people.
The patients with family risk need regular diagnosis, e.g. mammography, colonoscopy and skin examination.
In the future some genetic factors will be defined and possibly eliminated by genetic engineering.
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