Many breast cancer patients can safely avoid chemotherapy with new gene test, say scientists

Millions of breast cancer patients could now safely skip chemotherapy and be treated with hormone therapy alone. This is possible as scientists developed a DNA or gene test that can differentiate between patients who are likely to benefit from the treatment and those who are not, a clinical trial has shown.

According to a trial conducted by University College London (UCL), a revolutionary new genomic test can reliably identify which women will benefit from chemotherapy and which will not.

The press note by Eurekalert states that Chemotherapy is regularly offered to people with early‑stage breast cancer that has spread from the breast to nearby lymph nodes, as it lowers the risk of the disease returning.

However, several doctors raised concerns that many people with the most common, hormone‑sensitive type of breast cancer receive little or no benefit from chemotherapy, but still experience its significant and sometimes dangerous side effects.

Though chemotherapy can help fight some forms of the cancer, it can come with a range of side effects, including hair loss, nausea, insomnia, fatigue, and even infertility and cognitive impairment.

The study, led by University College London (UCL), involved more than 4,400 newly diagnosed patients aged 40 or older across the UK, Norway, Sweden, Australia, New Zealand and Thailand.

According to Eurekalert press release, the OPTIMA trial recruited women and men aged 40 or older following surgery for hormone-sensitive breast cancer.

"Most had their cancer spread to underarm lymph nodes, which placed them at high risk of future recurrence. Because of this, their usual treatment included both a course of chemotherapy and standard hormone tablets taken for five to ten years," the statement added.

According to the BBC, scientists used a gene test called Prosigna to measure the activity of 50 genes involved in breast cancer growth and calculate a patient's risk of the disease returning.

Those who received a low score - two-thirds of the group - were not treated through chemotherapy.

The five-year survival rate of their group was 93.7 percent, compared with a 94.9 percent rate among patients who received chemotherapy as part of their care, the report added.

"The results show that people aged 40 or older with hormone‑sensitive breast cancer and a low Prosigna score can safely avoid chemotherapy," the press note read.

OPTIMA "addresses a long-standing challenge in breast cancer care: identifying who truly benefits from chemotherapy and who does not," Professor Rob Stein, the chief investigator of the OPTIMA trial and professor of Breast Oncology at the UCL Cancer Institute was quoted in the press note as saying.

Stein added, "Our findings show that many patients can safely avoid chemotherapy without compromising their outcomes."

“These results mark an important and significant step toward more personalised treatment. The trial has successfully used tumour biology to guide decisions rather than relying solely on traditional clinical features," Stein said.

"For patients, this means many may be spared the physical and emotional burden of chemotherapy and its potential long-term side effects. For health systems, it represents a more efficient and evidence-based use of resources,” Stein added.

The team cautioned that it is not yet known whether the findings apply to people under the age of 40.

The next phase of OPTIMA aims to generate further information about test use for premenopausal women but a result is still several years away.

Co-chief Investigator and Professor of Breast Oncology at the University of Glasgow, Professor Iain MacPherson, said: “OPTIMA provides robust, practice‑changing evidence that we can safely reduce the use of chemotherapy for many patients with hormone‑sensitive breast cancer.

“These findings represent a major step forward in delivering more personalised, precise care, ensuring that treatment decisions are driven by what will genuinely improve outcomes for patients, while avoiding unnecessary toxicity. The potential impact for both patients and health services is substantial," Iain MacPherson said.

The study will be presented at 2026 American Society of Clinical Oncology (ASCO) meeting in Chicago this month.