Multiple genetic changes are necessary for the development of cancer, most clearly exemplified by the stepwise genetic changes shown by many colon polyps progressing to cancer. The exponential rise in many cancers with age fits with an increased susceptibility to the late stages of carcinogenesis by environmental exposures. Controversy continues over whether cancer is less aggressive in the elderly. Yet, death occurs with smaller tumor burdens. The part of cancer prevention we know the most about is the avoidance of toxins that induce or promote cancer.
Induction refers to the earliest genetic change induced by a carcinogen.
Promotion refers to cell growth induction that fixes and then further alters the genetic abnormality. Both may be necessary to create a cancer. Since prolonged exposure is one of the necessary ingredients to both induction and promotion, prevention of cancer in the elderly must begin before people become old. The best evidence strongly recommends avoiding smoking, overuse of alcohol, and exposure to known toxic chemicals. Hormonal exposure is implicated in the development of breast, prostate, and uterine cancers.