Only 5 to 10 percent of cancers are inherited. Such individuals inherit a cancer-predisposing mutation in all their cells, and then a somatic (body) cell undergoes a second mutation that initiates the disease. The second mutation may be spontaneous or in response to an environmental factor such as smoking.
The one-two punch of inherited cancers, called the 2-hit hypothesis, was first described in 1971. (more…)