By Robbie Owens

DALLAS (CBSDFW.COM/AP) –  There is new hope for patients battling a particular type of breast cancer –– and it’s coming in the form of what doctors are calling a ‘smart bomb’.

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“It really hits a target, rather than just blasting away at the whole thing. You’re really focusing on the cancer cells and minimizing side effects, minimizing damage to healthy tissue and .. and hitting the cancer hard which is exactly what we want to do,” says Dr. John Pippen, with Texas Oncology in Dallas.

The drug called T-DM1 treats patients diagnosed with what’s called HER2 positive breast cancer. HER2 is a protein found on the surface of some breast cancer cells. Having too much of that protein causes cancer cells to grow and spread quickly.

In a key test involving nearly 1,000 women with very advanced disease, the experimental treatment extended by several months the time women lived without their cancer getting worse, doctors reported a cancer conference in Chicago over the weekend.

More importantly, the treatment seems likely to improve survival; it will take more time to know for sure. After two years, 65 percent of women who received it were still alive versus 47 percent of those in a comparison group given two standard cancer drugs.

That margin fell just short of the very strict criteria researchers set for stopping the study and declaring the new treatment a winner, and they hope the benefit becomes more clear with time. In fact, so many women on the new treatment are still alive that researchers cannot yet determine average survival for the group.

“The absolute difference is greater than one year in how long these people live,” said the study’s leader, Dr. Kimberly Blackwell of Duke University. “This is a major step forward.”

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A warning to hopeful patients: the drug is still experimental, so it is not available yet. Its backers hope it can reach the market within a year.

The treatment builds on Herceptin, the first gene-targeted therapy for breast cancer. It is used for about 20 percent of patients whose tumors overproduce a certain protein. But, doctors say T-DM1 has fewer side effects and patients don’t lose their hair.

Frisco Mom Erin Struck was diagnosed with HER2-positive breast cancer two years ago. Along with chemo and radiation, her treatment plan also included Herceptin. But, T-DM1 builds on that.  “I was the lucky one… I got to fight it,” says Struck.

Struck is now doing well and has completed her course of treatment. “I feel like I just did what I needed to do to get healthy for my family.” And she’s happy to hear that doctors will soon have more tools in their arsenal to return other patients to their families.

Dr. Pippen calls the development an exciting day in the fight against breast cancer.

The Herceptin hits the target of the HER2 and attached to it is the smart bomb, a drug called Emtansine that by itself is too toxic to give.  But when you hook together a tiny amount of this drug with Herceptin, then you’ve created a smart bomb.
And just maybe– a new batch of survivors.

“I will never look back,” says Struck. “I will just focus on my family, and my healthy future.”

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Copyright 2012 CBS Local.  The Associated Press contributed to this report.