Many agents have been identified and are often associated. Conceptually, there are 2 types of agents that promote cancer, responsible for cell mutations (mutagens) and those who are responsible for promoting the transfer. Some factors, like tobacco, are both mutagens and promoters.
Chemical
They are very numerous, and the leader in tobacco is responsible for most cancers of the lung.
Tobacco remains the leading cause of cancer, of course, lung cancer and airways but beyond digestive cancers, kidney, urinary …
Alcohol is involved, particularly in the development of gastrointestinal cancers, but beyond in cancers of the oral cavity, larynx and even the female breast.
The frequent association of alcohol and tobacco consumption constitutes the largest share in the origins of cancer deaths.
Occupational Pathology recognizes many cancers due to chemical or environmental:
* Skin cancer: arsenic, pitch, tar and oil, coal.
* Head and neck cancers: timber, nickel, chromic acid, zinc chromate.
* Broncho-pulmonary and pleural: asbestos, silica, arsenic, nickel, iron oxide.
* Bladder cancer: aromatic amines, dyes derived from benzidine.
* Liver cancer: arsenic, vinyl chloride monomer
* Prostate cancer: cadmium
* Brain tumors: nitrosated derivatives
* Leukemia benzene
Habits and Lifestyles
It is now apparent that the excess of certain fats in the diet and smoking and excess salt are contributing factors in the occurrence of cancerous diseases, particularly in the digestive tract.
Radiation
Radiation is involved in the occurrence of cancers in that they cause changes within the cell nucleus by DNA damage.
Skin cancers are more frequent among subjects exposed to sunlight.
The nuclear accident at Chernobyl released cesium and radioactive iodine. The thyroid iodine selectively fixed and the number of thyroid cancer has increased (2,000 cases could be attributed to the accident) in areas affected by the nuclear cloud.
Hormones, Viruses, Parasites
Hormones
Estrogens, female hormones are a factor of growth of some cancer cells
Virus
15% of human cancers have a viral cause established
* Certain leukemia and lymphoma
* Epstein Barr virus is associated with Burkitt’s disease, some cancers of the nasopharynx, some Hodgkin’s disease (variety of lymphoma)
* Virus hepatitis B and C is involved in the occurrence of primary liver cancer
* The papilloma virus, sexually transmitted diseases, are involved in cervical cancer
* HIV / AIDS is involved in the occurrence of Kaposi’s sarcoma and malignant lymphoma non-Hodgkin
Parasites
Schistosomiasis caused by Schistosoma haematobium, a parasite of African waters in the East, is involved in the occurrence of bladder cancer.
Genetic factors
Genetic factors are implicated in cancers called “hereditary”, related to genetic transmission of the mutation: some breast and colon. They represent 5% of all cancers.
Some environmental habits are involved in the occurrence of cancers known family, without putting in evidence of transmission of specific genes.
The mycobacterium tuberculosis rarely affects the middle ear (TOM) and mastoid. The increasing incidence of tuberculosis both our country and the U.S. is associated with an increased frequency of occurrence of TOM.