Scientists from Johns Hopkins University, in Baltimore, Maryland, say their discovery could help to develop treatments to fight a host of cancers including, leukaemia, lymphoma, breast, lung and prostate cancer.

Their work centred on the "myc" family of genes. Scientists have long known that these genes play a prominent role in tumour formation.

But the Johns Hopkins team focused on one member of that family, the c-myc. By doing this, they found that another gene, the HMG-I/Y gene is a key genetic "target" for tumour formation.

The team injected cells with increased HMG-I into mice and found they formed cancerous tumours. They also found that blocking the expression of the gene reversed abnormal growth of the tumour.

Dr Linda Resar, an assistant professor in the division of paediatric haematology at Johns Hopkins University School of Medicine, said this showed the gene may cause cancer. "Taken together, these findings suggest that HMG-I/Y genes may represent a new class of cancer-causing genes, or oncogenes."

The discovery could be particularly important in fighting the aggressive childhood cancer Burkitt's lymphoma.