If you have a 5% of dying in transit or at Mars due to equipment failure, as well as a 2% increased chance of getting cancer at some time in the future, the first obviously is the one to worry about.
It's going to be dangerous enough on Mars, without adding those factors in. Worse, it's going to be difficult if the person who dies is in a critical position. You would have some redundancy in personnel, but that's costly in terms of Delta-v too, for them, and for everything it takes to keep them alive.
