A gene discovery compared with “finding gold” could lead to new ways of diagnosing and treating the most common form of breast cancer, it was claimed yesterday.

Scientists identified three genes linked to hormonal breast cancer, which affects 37,000 UK women each year.

Four out of five breast tumours fall into this category and are fuelled by the female hormone oestrogen.

The new genes were found “next door” to the oestrogen receptor gene, the main driver of hormonal breast cancer, which has been studied for decades.

Biochemical changes leading to tumour development are triggered when oestrogen binds to the receptor molecule on cells.

Anita Dunbier, one of the Breakthrough Breast Cancer re-searchers at the Institute of Cancer Research in London, said: “This is a surprising discovery. We found these genes in a place we thought we knew a lot about – it is like finding gold in Trafalgar Square.

“We now have to look further at how these genes work, but the discovery could lead to possible new therapies that will benefit women with breast cancer in the future.”

The research is reported in the online journal Public Library of Science Genetics.

The scientists analysed the DNA of 104 patients with hormonal breast cancer looking for links to the oestrogen receptor.

Three genes, C6ORF96, C6ORF97 and C6ORF211, were found that appeared to influence the receptor but operated separately from it.

Their activity is unlikely to be affected by current treatments such as tamoxifen which target the oestrogen receptor. This means they could be potential targets for new drug treatments.

C6ORF211 was shown to drive the growth of tumours, while C6ORF97 provided an indication of treated cancer not returning.

Less is known about the third gene, C6ORF96, which is still being studied by the team.