Our current understanding of what causes cancer is not complete. It is clear that cancer is not caused by injury such as a bump or a bruise. Although being infected with certain viruses may increase the risk of some types of cancer, cancer is not contagious; no one can catch cancer from another person.
Cancer develops gradually as a result of a complex mix of factors related to environment, lifestyle and heredity. Scientists estimate that 80% of all cancers are related to the use of tobacco products, what we eat and drink, and to a lesser extent, cancer causing (carcinogens) agents in the environment and workplace. Some people are more susceptible to factors that can cause cancer.
Keep in mind that not everyone with a risk factor will get cancer. Most people do not. Below are some factors known to increase the risk of cancer:
Tobacco causes cancer. Smoking cigarettes, pipes or cigars, using smokeless tobacco or being regularly exposed to tobacco smoke, causes up to one-third of all cancer deaths.
Smoking accounts for more than 85% of all lung cancer deaths. The risk of developing lung cancer is affected by the number and type of cigarettes smoked and the numbers of years a person has been smoking. Smokers are more likely than nonsmokers to develop larynx (voice box), oesophagus (gullet), pancreas, bladder, kidney, cervix and lung cancers. The risk begins to decrease when a smoker quits.
Chewing tobacco can also cause cancers of the mouth and throat.
Exposure to environmental smoke increases the risk of lung cancer. The risk goes up 30% for the nonsmoking spouse of the person who smokes.
What a person eats may affect his chances of developing cancer. There is a link between a high-fat diet and certain cancers, such as cancer of the breast, colon, uterus, and prostate. Being seriously overweight is linked to increased rates of cancers of the prostate, pancreas, uterus, colon, and ovary. On the other hand, foods containing fiber, such as fruits, vegetables, whole-grain breads and cereals, help to protect against some types of cancer.
Drinking large amounts of alcohol increases the risk of cancer of the mouth, throat, oesophagus and larynx (voice box). People who smoke and drink have a higher risk. Alcohol can also damage the liver and increase the risk of liver cancer.
Being exposed to chemicals such as asbestos, nickel, cadmium, uranium, radon, vinyl chloride, benzidene, and benzene can increase the risk of cancer. It is important to follow safety and work rules to avoid contact with dangerous materials.
