BEIJING, June 15 (Xinhuanet) -- Scientists have discovered a breast cancer gene 30 to 40 percent of all breast cancers need to survive, offering what could be the biggest gene target yet for "smart bombs" to treat these tumors.

    The research was to be published today in the journal Cell.

    "If there's a 10 percent chance that this leads to a treatment for breast cancers that's going to be effective for 30 percent of women, in our way of measuring things that's a big advance." says Dr. Steven Narod, a University of Toronto professor and co-author of the original paper that identified the BRCA1 gene.

    Researchers say the gene is needed for survival by 30 percent to 40 percent of all breast cancers, and could present the biggest gene target yet for "smart bombs" to treat these tumors.

    Herceptin, considered the largest breakthrough for breast cancer in the past 15 years, and Gleevec, a drug that has revolutionized the treatment of leukemia and some gastrointestinal tumors, also work by shutting down a single mutant gene.

    This gene is different from the breast-cancer susceptibility genes, BRCA1 and BRCA2, which women are born with.

    Women who inherit mutated forms of those genes are at increased risk of developing breast cancer earlier in life.

    In this case women are born with a healthy version of the new gene, dubbed IKBKE, but a mutation occurs during life that causes it to churn out too many copies of itself in breast cells, but nowhere else in her body.

    The new breast cancer gene "plays a crucial role in the formation and survival of tumors," Hahn said.

    (Agencies)