A new mechanism behind cancer spread has been discovered that challenges the conventional view about what drives tumours.

Scientists investigating ovarian cancer found that a protein imbalance within cells switched on a biological circuit promoting growth and spread of the disease.

The findings are seen as important because they shine a spotlight on a cancer-driving factor other than genetic mutations.

Faults in the genetic code are generally seen as the main triggers of all cancers.

John Ladbury, from the University of Leeds, said: “There has been huge investment in sequencing the human genome with the idea that if we get all the relevant genetic information we can predict whether you have a predisposition to cancer and, ultimately, use a precision medicine-based approach to develop a therapeutic approach.

“Our study demonstrates that genetic screening alone is not enough.”

The study, published in the journal Oncogene, focused on a signalling pathway within cells called Akt that triggers and spurs on cancer.

An imbalance between two proteins was found to switch on Akt, leading to uncontrolled tumour proliferation in laboratory cell lines and mice.

In women with ovarian cancer, 10 per cent of those with the ‘wrong’ balance of proteins survived for seven years compared with 40 per cent who had the ‘right’ balance.