"The study should have a huge impact on doctors and patients", said Dr Kathy Albain, one of the main co-authors. The findings indicate that chemotherapy may be considered for the remaining 30% of women. "It helps direct patients to the right therapy, so that we're treating the right people with the right therapy at the right time". According to NPR, 65,000 breast cancer patients every year fall into that middle ground group.
"Chemotherapy is no Shangri-La", Brawley said.
This week, a trial showed that men given just months or weeks to live after being diagnosed with prostate cancer are surviving for more than a year thanks to a breakthrough in immunotherapy treatment.
"I will explain that's why research is so important in helping us move forward in breast cancer care that's how we will achieve a cure for breast cancer", Figueredo said.
"By stratifying these breast cancer patients [by risk] and finding that only those with the highest risk of recurrence need to have chemotherapy based on their tumor genetics, TAILORx shows great potential to ensure more gentle treatment without compromising its effectiveness", Purushotham told Live Science.
With the results of this trial doctors now have a clearer answer for how to tailor treatment for most women with the most common type of early stage breast cancer.
Results from this study suggest many women with this specific type of tumor do not receive any additional benefit from having chemotherapy in combination with endocrine therapy, compared to endocrine therapy alone. A score lower than 10 means the risk of distant recurrence is low, and the women will not benefit from chemotherapy.
One difference: In women 50 or younger, chemo was associated with a lower risk of cancer recurrence, although the rates of overall survival were similar. Women were separated into 2 groups, one receiving only hormone therapy, the other receiving chemotherapy and hormone therapy. She's still cancer-free two years later. Ten years later it came back and had spread. But although Mall returned to health soon after her surgery and remains cancer-free today, she said she was haunted by the uncertainty of her decision.
While the USA doctors who developed the therapy can not be sure how much the infused immune cells contributed to her recovery, the use of pembrolizumab alone has not been very effective for advanced breast cancer in the past.
Dr Simon Vincent, director of research at the charity Breast Cancer Now, warned more patients will have to be treated to assess how effective the therapy is.
"I don't know any doctor who isn't excited about this", he said. Prof Alan Melcher, from the Institute of Cancer Research in London, said: "This treatment represents a remarkable success in terms of translating our basic biological understanding of how the immune system responds to cancer into a real treatment of real benefit.' Peter Johnson, professor of medical oncology at Southampton General Hospital, said that "even cancers that have spread to different parts of the body may be treatable".
Through genetic testing, they separated women more likely to have recurrent cancer, which could potentially spare thousands from the treatment.
The dramatic success has raised hopes that the therapy will work in more patients with advanced breast cancer and other hard to treat cancers, such as ovarian and prostate.
A patient's tumour is genetically analysed to identify the rare changes that might make the cancer visible to the immune system.