About 240,000 new cases of breast cancer will be diagnosed in this country this year, and a lot of people assume the diagnosis automatically means chemotherapy treatment.
For about half of breast cancer cases, there's now a genetic test that can help women and their doctors decide whether they'll be able to avoid the dreaded chemo.
Last year, after Eleanor Garrity felt a lump in the shower and got the news she was fearing, she had a mastectomy. She was sure the next step would be pretty awful.
"I was 95 percent sure I was going to get chemo. I was very scared. I don't do well with antibiotics and medicine. It upsets my stomach. It makes me sick," she told ABC News' Kate Snow.
Then a simple test changed everything. Doctors analyzed the genetic makeup of her tumor and the results showed that in her case less invasive hormonal therapy would probably be enough to prevent her cancer from returning.
Instead of months of chemotherapy, fatigue, nausea and other side effects, she'd take one pill a day for five years.
"Once you know it's going to take care of the cancer, hey, it's one little pill. I can deal with it," she said.
Dr. Patricia Ganz is the director of the Division of Cancer Prevention & Control Research at UCLA Jonsson Comprehensive Cancer Center.
"In the last year or two with using these kinds of tests, I've been able to confidently tell patients that it is not just my opinion that they need chemotherapy or they don't need chemotherapy but we have another biological set of evaluations that really personalize it to their situation," Ganz said.
For more than 30,000 mainly younger women — under 70 — the test has revolutionized the way doctors decide on treatment.
"It's a very big deal because this can eliminate a lot of the guesswork that now goes on in terms of treatment recommendations," said Dr. Joseph Sparano, director of the Breast Evaluation Center and Breast Medical Oncology at the Montefiore-Einstein Cancer Center in New York.
In the past, with limited information, doctors would usually recommend chemo.
"That's the problem, is that in order to be conservative, we err on the side of overtreating," Sparano said.
Even with this genetic test, there is a gray area. Only about 30 percent to 50 percent of patients will get a definitive answer. The rest may need chemo or may not.
Researchers are studying patients in that middle zone, with the hope they can refine treatment even more.
Ganz said, "I think we are really heading into a field called personalized medicine. And while it makes some sense that every cancer is unique, we didn't have the tools before to do that," Ganz said.
As for Garrity and her prognosis, she said she's feeling confident. "I'm going to be just fine."