Lead author Dr Joseph Sparano, of Montefiore Medical Centre in NY, said: "Any women with early stage breast cancer 75 or younger should have the test and discuss the results of TAILORx with her doctor".
The new study of almost 7,000 women found that use of the already available Oncotype DX gene test could pinpoint those women who needed chemotherapy, and those who did not. After years of follow-up, the data showed that most patients who did not get chemotherapy fared as well as those who did.
The result: After an average follow-up of 7.5 years, the researchers saw no added benefit in this group to adding chemotherapy to the treatment mix.
For example, another study at the conference found that Merck's immunotherapy drug Keytruda worked better than chemo as initial treatment for most people with the most common type of lung cancer, and with far fewer side effects.
The study, which used genetic testing and included about 10,000 patients, revealed that women with smaller-sized, estrogen-fueled tumors that had not spread to the lymph nodes fared just as well without chemo as those who received it. Or was it sufficient for them to be treated only with endocrine therapy, which blocks the cancer-spurring properties of hormones?
"We'll give women in this group about six months of chemotherapy", Brawley said.
"Patients really struggle having to make that decision, and now they don't have to".
"We have been waiting for these results for years", said Allison Kurian, an oncologist at Stanford University who wasn't involved in the trial.
Arsenal in shock move for Manchester United midfielder
Departing Manchester United midfielder Marouane Fellaini is pricing himself out of a move to PSG . Fellaini has also been linked to Paris Saint-Germain and Marseille.
"The more in the bad risk category we'd say the chances of the cancer coming back are high so we'd give aggressive chemotherapy but still it wasn't an accurate science", explained Dr. Imran.
The study found that for participants with gene test scores between 11 and 25 - especially among women ages 50 to 75 - there was no significant difference between the chemotherapy and no chemotherapy groups.
Each year more than 20,000 women in the United Kingdom are diagnosed with hormone-receptor positive, HER2-negative, node-negative breast cancer.
She had undergone a mastectomy in 2003 after the cancer was first diagnosed.
"My condition deteriorated a lot towards the end, and I had a tumour pressing on a nerve, which meant I spent my time trying not to move at all to avoid pain shooting down my arm", Ms Perkins said.
She agreed to take part in a clinical trial with the National Cancer Institute to try a new treatment involving immunotherapy. Oncotype DX has spurred the trend, and is likely to accelerate it.
For the youngest participants, chemotherapy was only slightly more effective for women with scores between 16 and 25.
Women at low risk could skip chemo.
"Tumors grow more aggressively in premenopausal women, not just women under 50", Brawley said.
In this latest study, researchers focused on the 69 percent of the clinical trial's participants who had mid-range test scores.