Cancer

Cancer is the result of changes in the genetic material of a cell that cause the cell to gradually lose the ability to grow in a regulated fashion. These changes can be brought about by contact with harmful environmental agents or by inheritance of genes leading to a genetic predisposition.

Cancer risk increases with age, as the probability of accumulating mutations in the DNA increases with time. Environmental factors include lifestyle (e.g., smoking), diet (e.g., saturated fats from red meat), and exposure to certain chemicals (e.g., asbestos, benzopyrenes), ionizing radiation (e.g., X-rays, radon gas), ultraviolet radiation (e.g., sun, tanning beds), and certain viruses (e.g., human papillomavirus, Epstein-Barr virus). Heredity also plays a role in oncogenesis, as mutations in certain genes increase the probability of developing certain types of cancer. For instance, women who inherit a mutated copy of the BRCA1 or BRCA2 gene have a greatly increased probability of developing breast cancer at a young age.