The main cause of cancer particularly because of internal factors:

External factors:

Chemical carcinogens such as polycyclic aromatic hydrocarbons (mainly exists in the modern industrial and modern transport emissions and cigarettes, Xunkao food); aromatic amines and azo dyes category (stored in the textile printing and dyeing, cosmetics); Asia Glass amines (widespread in the food system), metals (asbestos-containing products containing chromium compounds and polycyclic aromatic hydrocarbons of high, which can be carcinogenic).

Physical factors, such as ionizing radiation (including medical and occupational exposure); long-term exposure, such as the sun.

Biological factors, such as Aflatoxin (found in mouldy peanuts, corn); virus (human herpes virus, EB virus, hepatitis B virus, etc.); parasites (Xixue Chong, etc.).

Internal factors:

The lower immune function;
Large, long-term hormone;
Nervous system disorders (mental and emotional tension in long-term poor, to endocrine disorders);
Genetic factors (liver cancer, nasopharyngeal cancer, and other families with a genetic phenomenon).

Prevention:

Reduce chronic stimulation: stop smoking, avoid drinking alcohol, eat too hot and provocative-food.
Infection control: prevention and treatment of hepatitis B and schistosomiasis, and other cancer-related diseases.
The timely treatment of precancerous lesions: such as chronic ulcers, chronic atrophic gastritis, such as colon polyps.
Avoid eating food containing carcinogenic substances: if mouldy peanuts, grain, salted products, preservatives.
The consumption of vitamin-rich large number of A, B, C and E of food: fresh vegetables from the main intake.

A balanced diet: fresh multi-fiber foods, to avoid.
Develop long-term the good habit of tea drinking, especially green tea.
Attention to personal hygiene: to maintain mood, appropriate exercise, avoid the use of carcinogenic substances in cosmetics, hair dyes, and so on.