Knudson's insight was to compare the incidence of retinoblastomas, including the number of tumors, the ages of occurrence, and whether tumors occurred in both eyes, among children in families with and without hereditary predisposition to retinoblastomas.
12.
Because two hits are less likely than one to occur during a person's lifetime, the risk of an inherited breast cancer is much greater than the risk of a cancer that develops without any hereditary predisposition.
