His team is scheduled to present the study findings Sunday at the ASCO annual meeting, in Chicago, and the study is also being published simultaneously in the New England Journal of Medicine.
"We can spare thousands and thousands of women from getting toxic treatment that really wouldn't benefit them", said Dr Ingrid A Mayer, from Vanderbilt University Medical Center, an author of the study.
He said: This is a remarkable and extremely promising result, but we need to see this effect repeated in other patients before giving hope of a new immunotherapy for incurable metastatic breast cancer.
Rosenberg says investigators have already tested the approach in liver and colorectal cancer, but the "big picture" is that it is not cancer type-specific. Dr. Jennifer Ashton, ABC News" Chief Medical Correspondent, says, "This is for the woman at intermediate risk for that cancer to reoccur.
Rachel Rawson, from the charity Breast Cancer Care, said: "Every day, women with certain types of breast cancer face the bad dilemma of whether or not to have the treatment, without hard facts about the benefit for them".
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Each year more than 20,000 women in the United Kingdom are diagnosed with hormone-receptor positive, HER2-negative, node-negative breast cancer. And while this finding certainly doesn't eliminate chemotherapy as a viable tool, it very likely means that a huge number of patients will have the opportunity to receive more personally-tailored treatments in the future.
After five years, 92.8 percent of the women who received hormone therapy alone, and 93.1 percent of those who received hormone therapy plus chemotherapy, were cancer-free.
"Many women with breast cancer will be able to be spared unnecessary chemotherapy", said Dr. Erna Busch-Devereaux, a breast surgeon at Northwell Health's Huntington Hospital, in Huntington, N.Y.
Thirty percent of the women in the trial did have evidence of cancer hiding in their bodies.
"Oncologists have been getting much smarter about dialing back treatment so that it doesn't do more harm than good", Steven Katz, a University of MI researcher who examines medical decision-making, told the Washington Post. Exploratory analyses did suggest that the addition of chemotherapy was associated with some benefit for women 50 years of age or younger who had a recurrence score of 16 to 25, but not for those whose score 15 or lower.
About 17 per cent of the women had scores that showed they were at high risk of recurrence so they were advised to take chemo.
The treatment is not only expensive but physically demanding and several other patients in the clinical trial died during treatment, including several who succumbed to side effects. Newer care includes gene-targeting therapies, hormone blockers and immune system treatments.
If doctors adopt the study's findings, a lot of women could be affected.
Until now, chemotherapy was highly recommended with a result greater than 25, and below 10 it was not.
Using a pioneering antibody technique, medical researchers have completely eliminated advanced breast cancer from a 49-year-old woman.
Although this work does indicate that thousands of women can be spared this hard treatment, it doesn't mean skipping chemo is the right choice for all early-stage breast cancer patients. It's called the Oncotype DX test.
This US postal stamp helped fund key breast cancer study
After years of follow-up, the data showed that most patients who did not get chemotherapy fared as well as those who did. Very high scores are at increased risk of the cancer spreading, and those patients have benefited a lot by chemotherapy.