They found a significant decrease in a marker associated with cell damage, which can cause impaired brain, muscle, liver and kidney function as well as ageing effects on the skin.

This protein is often produced when nerve cells are reacting to neurotransmitters and is thus regarded as a general marker for nerve-cell activity.

But it is an open question, given all the genetic damage in a cancer cell, as to which type of damage would be the best marker of a tumor's presence.