The risk of neoplastic HSC disorders when a mutant (cancer) stem cell is present at birth. We plot the probability of diagnosis during the lifespan as a function of the mass of the mammal (using the same color codes as in Figure 1) for the case when the mammal is already born with a single CSC due to mutation. Consequently, in these curves selection plays a more important role than mutation during the life of the animal. Only for small values of r does the probability of diagnosis decrease monotonically, and already for moderate values of r the probability remains constant for over 2 orders of magnitude of mammalian mass, further increasing for large values of M.