The gene has a couple of relatives called A-Raf and B-Raf which work in a similar way and also help to trigger cell division. Scientists suspected that the more cancer cells relied on Raf-1, rather than its relatives, the more they would be affected by Raf-1 targeted therapies.

Genes exert their effects by producing specific protein molecules, so researchers measured the Raf-1, A-Raf and B-Raf proteins in different ovarian cancer cells. Cells with the highest proportion of Raf-1 were the most sensitive to treatment, providing the basis of a test to identify patients who would be best suited to therapy.

Dr Langdon adds: "It's crucial with selective cancer therapies that we have a way of picking out the patients who would benefit most, so that doctors have a rational basis for giving patients a particular treatment. Our results certainly suggest it would be possible to select patients for Raf-1 therapy." Clinical studies with anti-Raf-1 therapies are underway and scientists believe their greatest areas of promise may be in combination with conventional chemotherapy.

Professor Robert Souhami, Cancer Research UK's Director of Clinical and External Affairs, says: "The future of cancer treatment lies in selective therapies, which target only the cancer cell, and often only certain types of cancer cell, while leaving healthy tissue unharmed. "While this research is still at an early stage, it is laying important groundwork for the development of selective and more effective treatments for a particularly insidious form of cancer."