Durrett, Rick et al., A waiting time problem arising from the study of multi-stage carcinogenesis, Annals of applied probability , 19(2), 2009, pp. 676-718
We consider the population genetics problem: how long does it take before some member of the population has m specified mutations? The case m=2 is relevant to onset of cancer due to the inactivation of both copies of a tumor suppressor gene. Models for larger m are needed for colon cancer and other diseases where a sequence of mutations leads to cells with uncontrolled growth.