PHILADELPHIA — Scientists have associated three signaling pathways in cells with the risk of getting breast cancer, opening the door for someday developing a drug that might prevent the disease.

Drugs that may lower some people's risk of getting cancer — called chemoprevention drugs — should be tested for how well they target these pathways, now that the pathways are known to lead to disease, researchers said.

It would be hard to measure the success of a preventive drug without knowing what the drug was acting on, because no one can be sure they would get cancer without it, the scientists noted.

The discovery that these pathways are linked to the development of breast cancer could be used to gauge the success of chemoprevention drugs in clinical trials, said study researcher Dr. Victoria Seewaldt, director of the prevention program at the Duke University Comprehensive Cancer Center.

If scientists had never found these specific pathways, Seewaldt said, the only way to evaluate a chemoprevention drug would be through an unwieldy clinical trial. Researchers would have to "round up 10,000 to 20,000 women for five years, and give them one dose of one drug, and then see if there are problems" — too long a time for too small a result.

"The problem with that," she said of such a drug trial, "is everyone gets cancer differently, and we have no idea why it fails if it does."

By finding a drug that lowers the rate of signaling in these three pathways, it could be possible to lower the risk of breast cancer, Seewaldt said.

To try to find signaling pathways, Seewaldt and fellow researchers tested the network of signaling molecules in the cells of 100 women who had a high risk of breast cancer.

By finding how the signaling molecules interact, it's possible to see the impact that a chemoprevention drug would have on activity of the pathways, Seewaldt said.

As an illustration, she said there are many ways to go from Philadelphia to New York City. A roadblock (a cancer prevention drug) could be put up on one of the routes, but the traveler (a "smart" pre-cancer cell) could bypass the roadblock by using another route.

That's why it's important to see, in detail, why some signaling pathways go wrong, Seewaldt said.

"We need to know the biology" in order not to undertreat or overtreat patients, Seewaldt said.

With the knowledge of the pathways, a future drug could target and inhibit cell proliferation and invasion, she said.

The study was presented here at the Frontiers in Cancer Prevention Research Conference, held by the American Association for Cancer Research.

This article was provided by MyHealthNewsDaily, a sister site to LiveScience.