I've talked to some drummers who seem to have a very hard time staying in shape on the road, including some drummers touring with high-profile acts that don't have to live on fast food every night.
Astonishingly, in spite of decades of research, there is no agreed theory of cancer, no explanation for why, inside almost all healthy cells, there lurks a highly efficient cancer subroutine that can be activated by a variety of agents - radiation, chemicals, inflammation and infection.