Gene test guides more personalised breast cancer treatment

Many people with breast cancer can safely avoid chemotherapy with the use of a gene test, a large international clinical trial led by University College London (UCL) has found. 

The OPTIMA trial (Optimal Personalised Treatment of early breast cancer using Multi-parameter Analysis) followed more than 4,400 patients across the UK, Norway, Sweden, Australia, New Zealand and Thailand. 

The findings, presented at the 2026 American Society of Clinical Oncology (ASCO) meeting in Chicago, show that in people aged 40 and over with a low Prosigna score, only 2% will benefit from chemotherapy. 

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. While effective overall, there is concern among clinicians 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. 

OPTIMA used a genomic test from Veracyte called Prosigna, which measures the activity of genes involved in breast cancer growth. The test is performed on cancer tissue samples. Typically, these are tumours removed at surgery but as the test uses very little tissue, it also works on diagnostic needle biopsies. 

Chief Investigator of the OPTIMA trial and Professor of Breast Oncology at the UCL Cancer Institute, Professor Rob Stein said: “OPTIMA addresses a long-standing challenge in breast cancer care: identifying who truly benefits from chemotherapy and who does not. 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.” 

Results of the OPTIMA trial 

The OPTIMA trial recruited women and men aged 40 or older following surgery for hormone-sensitive breast cancer. Most had their cancer spread to under arm 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 10 years. 

Of the 4,429 people who took part in the trial, more than two-thirds (68%) had a low Prosigna score. For this group, the results showed that outcomes were very similar whether chemotherapy was given or not.  

Five years after treatment: 

• 94.8% of those who received chemotherapy alongside hormone therapy were alive and free from breast cancer recurrence 
• 93.6% of those treated with hormone therapy alone were also alive and recurrence-free 

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