• Excesses or deficiencies in diet, particularly high-fat and low-fiber diets.
• Obesity.
• Sexual practices, including the age of a woman when she first had intercourse and first becomes pregnant.
Certain sexually transmitted viruses can cause cancers, and the risk of catching one of these viruses
increases with unprotected sexual contact and with the number of sexual partners. This is particularly true for
AIDS related cancers such as Kaposi's sarcoma .
Promoters include:
• Alcohol, which is a factor in 4 percent of cancers, mainly in cancers of the head and neck and the liver.
• Stress, which may weaken the immune system . Stress is also relieved all too often with cigarettes, alcohol, rich
food and drugs.
Miscellaneous Factors include:
• Heredity.
• Weaknesses of the immune system.
When two or more hits are combined—tobacco smoke and asbestos exposure, or cigarette smoking and alcohol, for example— the chance of getting cancer is not the sum of the individual risks. Rather, the chances are multiplied. Cancer is an additive process with many different hits occurring and interacting over many years.
