Rinaldo Schinazi
University of Colorado, Colorado Springs
We propose a simple stochastic model based on the two successive mutations hypothesis to compute cancer risks. Assume that only stem cells are susceptible to the first mutation and that there is a total of $D$ stem cell divisions over the life time of the tissue with a first mutation probability $\mu_1$ per division. Our model predicts that cancer risk will be low if $m=\mu_1D$ is low even in the case of very advantageous mutations. Moreover, if $\mu_1D$ is low the mutation probability of the second mutation is practically irrelevant to the cancer risk. These results are in contrast with existing models but in agreement with a conjecture of Cairns.
In the case where $m$ is large our model predicts that the cancer risk depends crucially on whether the first mutation is advantageous or not. A disadvantageous or neutral mutation makes the risk of cancer drop dramatically.
