Genomic test may help some breast cancer patients avoid chemotherapy

Patients diagnosed with breast cancer may be able to safely avoid chemotherapy if a genomic test indicates they are at low risk of their cancer returning, according to findings presented at a major cancer conference.

Chemotherapy is commonly offered to people with early-stage breast cancer that has spread to nearby lymph nodes, as it reduces the risk of recurrence. The OPTIMA trial (Optimal Personalised Treatment of early breast cancer using Multi-parameter Analysis) evaluated whether a genomic test could help identify patients with the most common hormone-sensitive form of breast cancer who could safely avoid chemotherapy.

'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', said Professor Rob Stein, chief investigator of the OPTIMA trial and professor of breast oncology at University College London (UCL) Cancer Institute.

The study, sponsored by UCL and coordinated by the University of Warwick Clinical Trials Unit, enrolled 4429 patients aged over 40 years across six countries. Participants had newly diagnosed hormone receptor-positive, HER2-negative early breast cancer and had been recommended to receive chemotherapy. Patients were randomly assigned either to receive standard treatment or a treatment strategy guided by the Prosigna genomic test, which analyses the activity of 50 genes in tumour tissue to estimate the risk of the cancer returning. Among patients whose tumours were classified as low risk by the Prosigna test, the estimated five-year invasive breast cancer-free survival rate was 93.7 percent for those treated with hormone therapy alone, and 94.9 percent for those who received chemotherapy followed by hormone therapy.

The findings were presented at the 2026 American Society of Clinical Oncology's annual meeting in Chicago and have so far been published only as a conference abstract rather than a full peer-reviewed research paper. The researchers reported that the genomic test-guided approach was non-inferior to standard treatment, suggesting that many patients with low Prosigna risk scores may be able to avoid chemotherapy without substantially affecting their outcomes.

'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', Professor Stein added.

The trial had a median follow-up of 3.9 years. The researchers said the results could inform future guidance from the National Institute for Health and Care Excellence and support wider NHS access to the Prosigna test. The test can be performed in existing NHS laboratories using tumour tissue already collected during routine surgery or biopsy procedures.

Professor Iain MacPherson, a co-chief investigator and professor of breast oncology at the University of Glasgow, said: '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.'

The researchers estimate that more than 5000 NHS patients each year could avoid chemotherapy if the test is adopted in routine clinical practice.