What Causes Cancer?

Cancer occurs when there are changes in the genes responsible for cell growth and repair. These changes are the result of the interaction between genetic host factors and external agents which can be categorized as:

• Physical Carcinogens such as Ultra Violet (UV) and Ionizing Radiation
• Chemical Carcinogens such a Asbestos and Tobacco smoke
• Biological Carcinogens such as
• Infections by Virus (Hepatitis B Virus and Liver Cancer, Human Papilloma Virus (HPV) and Cervical Cancer) and Bacteria (Helicobater Pylori and Gastric Cancer) and Parasites (Schistosomiasis and Bladder Cancer)
• Contamination of food by Mycotoxins such as Aflatoxins (products of Aspergillus Fungi) causing Liver Cancer. Tobacco use is considered one major risk factor for cancer and causes a large variety of cancers such as lung, larynx, oesophagus, stomach, bladder, oral cavity and others.
  Although there are still some open questions, there is credible evidence that dietary factors also contribute to causing cancer. This applies to obesity as a compound risk factor per se as well as to the composition of the diet such as lack of fruit and vegetables and high salt intake. Lack of physical activity is yet another risk factor for cancer. There is strong evidence about alcohol causing several cancer types such as oesophagus, pharynx, larynx, liver, breast, and other cancer types.