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.
"A waiting time problem arising from the study of multi-stage carcinogenesis." Ann. Appl. Probab. 19 (2) 676 - 718, April 2009. https://doi.org/10.1214/08-AAP559