However, all the researchers involved are keen to stress that their finding falls a long way short of proof for this theory.

BBC: Clues to massive leukaemia rise

Davidson, a serial entrepreneur (he co-founded the non-profit company Cool People Care in 2006 and the Nashville-based Proof Branding Solutions in 2010), has a long-standing arrangement with stress.

FORBES: Do You Want To Simplify Your Life? An Interview With Sam Davidson