Tug-of-war between driver and passenger mutations in cancer and other adaptive processes
The authors generate a model of tumour growth by defining a fitness function, which depends on the number of driver and passenger mutations which have accumulated. The birth rate of cells is set by the fitness, and the total death rate saturates with the number of cells in the population. In the rare event that a driver mutation is generated, the population size increases rapidly. The population then decays due to the accumulation of passenger mutations which are assumed to reduce the fitness by a constant amount, per mutation. The resultant dynamics is a sawtooth, due to a tug-of-war between drivers and passengers. Their model predicts a critical population size, above which tumour growth is exponential, and below results in extinction.