Doctors should talk about breast cancer-reducing drugs with women and offer tamoxifen or raloxifene to those that have a high risk of cancer and aren't likely to suffer side effects, says a government-backed panel.

The drugs work by blocking the effects of estrogen in breast tissue, lowering the chance of hormone-related cancers. But they also increase the risk of blood clots and hot flashes, among other side effects - so they shouldn't be handed out to everyone, the US Preventive Services Task Force says in its new draft guidelines.

"Currently only a minority of women for whom the medication might be indicated are actually taking it," says Dr Mark Ebell, a member of the Task Force from the University of Georgia College of Public Health in Athens.