"We originally, years ago, just did surgery, and then for many many years, everybody got chemotherapy, and now we know that we have these anti-hormonal drugs and pills that women can take".
The study found that all women over 50 with this type of breast cancer could skip chemotherapy, a group that represented 85% of the study's population.
Organizations focused on curing breast cancer say chemotherapy is not a one-size-fits-all treatment anymore.
Physicians and healthcare researchers are optimistic that this new testing will save numerous patients from unnecessary chemotherapy treatments and its side effects.
The study, led by the Albert Einstein Cancer Center in NY, is a rare cancer breakthrough as it can save money and instantly change practice.
"We still need to be very cautious in our young patient population with breast cancer, anyone under the age of 50".
Approximately 17 percent of girls needed high-risk scores and have been counseled to have chemo.
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The official said they are prepared to "brief members on certain questions specifically raised by Ryan and other members". The department originally denied Congress access to any of the documents, citing national security concerns.
"The study should have a huge impact on doctors and patients - its findings will greatly expand the number of patients who can forgo chemotherapy without compromising their outcomes", said Kathy Albain, chair of oncology research at Loyola University School of Medicine, in Chicago, USA, and co-author of the study.
He says breast cancer patients fall into three categories: Low-risk, which does not require chemo, high-risk - which demands the treatment, and an intermediate category they call "the grey area", where he says this new research now clarifies.
Jane Murphy, clinical nurse specialist at Breast Cancer Care, said: "It's really interesting to see different avenues are being explored to help women adapt to life after breast cancer, which can be incredibly daunting and hard".
Chang said the results were exciting because chemotherapy before surgery has been adopted in other cancer types, such as breast and large bowel, and this study now provides evidence to suggest benefit for pancreatic cancer too.
"For women over 50, we can feel quite confident that using the data in this trial to prevent the use of chemotherapy for women with those scores".
Dr. Jennifer Litton at MD Anderson Cancer Center in Houston, agreed, but said, "Risk to one person is not the same thing as risk to another". Her hair fell out, she developed an infection and was hospitalized for a low white blood count, "but it was over fairly quickly and I'm really glad I had it". She said, "I was in the grey area". "I'm a firm believer in medical research".