  The meaning of public messages such as "One in x people gets cancer" or "One
in y people gets cancer by age z" can be improved. One assumption commonly
invoked is that there is no other cause of death, a confusing assumption. We
develop a light bulb model to clarify cumulative risk and we use Markov chain
modeling, incorporating the assumption widely in place, to evaluate transition
probabilities. Age-progression in the cancer risk is then reported on
Australian data. Future modelling can elicit realistic assumptions.
