Other efforts seek to improve genetic testing to provide more insight on patients' individual cancer risks, but that work may not be as useful as learning more about the disease itself, said Dr. Katherine Tkaczuk, director of the breast evaluation and treatment program at the University of Maryland's Greenebaum Cancer Center.

"It's not ever going to be possible to look at every gene, although we'd like to be personalized eventually," Tkaczuk said.

Developing better profiles of each breast cancer type, which Tkaczuk said she expects to number more than just the four outlined in the Nature study, can establish a better "common ground" to apply to all patients, she said.

In the realm of cancer research, much is known about breast cancer relative to other cancers, making targeted therapies more advanced, said Dr. Otis Brawley, chief medical officer for the American Cancer Society. But more could be done, he said, pointing out that the federal cancer institute funds only about 10 percent of research proposals.

"In breast cancer, we understand more about the targets than almost any other cancer," Brawley said. "I see a lot of progress. I'm not at all satisfied with the pace of that progress."

Part of the difficulty is that the deeper researchers delve into breast cancer types, the fewer patients their findings may help, doctors said. That also makes it difficult for researchers to get a large enough sample of patients from which to draw conclusions. Studies pull from hospital cancer centers across the country to gather a large enough pool of cases.

The treatments also are costly and not a quick fix. For Herceptin, for example, a full course is administered for a year and costs about $50,000. Combined with Perjeta, the new companion drug, the price rises above $100,000.

Still, patients are eager to embrace new treatments, Thompson said. A former nurse, Thompson started working as a nurse educator and navigator at Hopkins' breast center after completing her treatment, helping others learn more about their options.

Many go to their oncologists after doing their own research, asking specifically about targeted therapies that are in clinical trials, despite the time and costs involved.

"A year seems like a long time to not be able to put cancer behind you, but at the same time, they're glad to have that arrow in their quiver," Thompson said. "This is the best shot for what we call a curative paradigm."

sdance@baltsun.com

twitter.com/ssdance