London, (GUARDIAN NEWS SERVICE)

By Alok Jha

Scientists have found a better way to predict which breast cancers are likely to spread through the body. The discovery will give doctors a better idea of which patients need most attention and spare others from the side-effects of unnecessary treatment.

Most of the deaths attributable to tumours are a result of a process called metastasis, where the cells detach from the main cancer and spread through the body. The average survival of patients with metastatic breast cancer is between two and four years, compared with an 80% survival rate for women whose disease does not spread.

Writing in Monday's edition of the Proceedings of the National Academy of Sciences, Nigel Crawford of the National Cancer Institute in Maryland, in the US, said it was important for researchers to find a way to understand how cancers spread to identify those patients most at risk. "This in turn may permit development of therapies and initiation of more aggressive treatment in women with poorer prognoses to reduce the incidence and extent of metastatic disease. Conversely, it may also prove possible to identify women at low risk of metastasis, thus sparing them needless adjuvant therapy."

In his study he injected a gene for the protein Brd4 into mouse breast cancer cells known for their metastatic ability. He found that when the protein was present the cancer's ability to invade other body cells was reduced. His team compared these results against information from five groups of human breast cancer patients. They found that in all the groups patients with the human equivalent of Brd4 had longer survival rates and were less likely to have cancers that had spread, suggesting it was an accurate predictor of the severity of human breast cancers.

Julie Sharp, science information manager at Cancer Research UK, said: "This work suggests that measuring Brd4 gene activity could have a role to play, although more work is needed."