Chapters Index (French) French Version Welcome page Contact

Three different steps may be schematically described during cancerogenesis, the first two are only known through experimental models and epidemiological studies of human cancers:

• initiation is a rapid and irreversible DNA lesion which occurs after exposure to a carcinogen (physical carcinogen, chemical carcinogen, viral carcinogen)
  
• promotion is due to prolonged, repetitive or continuous exposure to substances which maintain and stabilise the initiated lesion,
  
• progression is the acquisition of non controlled multiplication properties, independence acquisition, loss of differentiation, local invasion and metastasis.

Schematic view of the first steps of cancerogenesis

The biological mechanisms involved throughout these three steps are described in Cours de Cancérologie fondamentale (in French).

Prevention of the initiation of the cancer process involves the protection of cells from carcinogenic agents like tobacco, benzol, various chemical products, radiation, and so on). Prevention is dictated by knowledge acquired through human epidemiological studies as well as experimental cancers in animals.

Preventing the promotion of the cancer process also involves protecting the organism from various products and situations, like alcohol, tobacco, viruses, local irritation processes, and so on). Prevention results from the same type of epidemiological and experimental studies. Knowledge of other diseases linked to developing cancers (such as genital infections or hereditary syndromes) also facilitates cancer prevention.

Preventing the progression of cancer is possible through the same studies but also by active, well designed policies for the screening of pre-cancerous lesions and small cancers, when policies are applicable.