Young women diagnosed with breast cancer may soon have another option to choose from rather than going under the knife.

Researchers at the Walter and Eliza Hall Institute of Medical Research in Australia believe they've found the kryptonite for the breast-cancer causing gene BRCA1 - believed to be the cause behind around half of hereditary cancers.

The answer lies in the ready-made drugs commonly known as Xgeva and Prolia, which are mainly used to treat osteoporosis.

New Zealand PhD student Emma Nolan is one of the researchers and said initial testing is promising.

She said right now women in their 20s and 30s are faced with the choice of having their breasts and, or ovaries removed and this may just be an alternative that maintains their fertility.

Ms Nolan said results so far show the drug prevents, and can even stop the growth of cancer but further trials have begun to confirm their findings, and ascertain if other genes are also susceptible to the drug.

It's hoped the further results will be available next year.