London, 31 May 2026 – A major international clinical trial has raised hopes that many breast cancer patients may be able to safely avoid chemotherapy, after researchers found that a genomic test could help identify those unlikely to benefit from the treatment.
The study focused on the Prosigna genomic test, which analyses the activity of 50 genes in tumour tissue to estimate the risk of breast cancer returning. The findings suggest that for many patients with hormone-sensitive breast cancer, treatment decisions can be guided more precisely by tumour biology rather than relying only on conventional clinical risk factors.
The trial, known as OPTIMA, involved more than 4,400 newly diagnosed patients aged 40 and above across several countries, including the United Kingdom, Norway, Sweden, Australia, New Zealand and Thailand. It examined whether patients identified as lower risk by the genomic test could avoid chemotherapy and receive hormone therapy alone without compromising outcomes.
The results showed that outcomes were broadly similar between patients who received chemotherapy and those who did not. Five years after treatment, 94.8% of patients who received chemotherapy alongside hormone therapy were alive and free from breast cancer recurrence, compared with 93.6% of those treated with hormone therapy alone.
Researchers said the findings indicate that many patients with a low Prosigna score can avoid chemotherapy safely, reducing exposure to side effects such as fatigue, nausea, hair loss, weakened immunity and fertility-related complications. The result marks a meaningful step toward more personalised breast cancer care, where treatment intensity can be better matched to the individual patient’s tumour profile.
The implications could be significant. Hormone-sensitive breast cancer is the most common form of breast cancer, accounting for a large majority of cases globally. For health systems, reducing unnecessary chemotherapy could lower treatment burden, free up medical resources and improve patient quality of life, while still preserving strong survival outcomes for those who do not need the additional treatment.
The study also strengthens the role of genomic testing in mainstream oncology. Instead of treating patients based mainly on tumour size, grade or lymph node involvement, tests such as Prosigna provide additional molecular information that can help doctors estimate recurrence risk and decide whether chemotherapy is likely to add meaningful benefit.
However, chemotherapy will remain important for patients whose cancer profile suggests higher recurrence risk or greater likely benefit from treatment. The significance of the trial is not that chemotherapy is becoming obsolete, but that it may no longer need to be used as broadly in patients whose genomic profile indicates limited benefit.
The findings were presented at the American Society of Clinical Oncology annual meeting, one of the world’s most closely watched cancer research gatherings. Oncology experts have described the results as potentially practice-changing, particularly because the trial included patients who were traditionally considered at higher clinical risk and therefore often directed toward chemotherapy.
For Asia, the development is especially relevant as cancer treatment systems face rising demand, cost pressures and the need for more targeted care pathways. Countries with expanding oncology services may increasingly look to genomic tools to improve treatment precision, although access, affordability and reimbursement policies will determine how quickly such tests become widely available.
The Ledger Asia Insights
The OPTIMA trial points to a future where cancer treatment becomes less about giving more therapy and more about giving the right therapy. For patients, the ability to avoid chemotherapy without materially worsening outcomes could mean fewer long-term side effects and a better quality of life. For healthcare systems, genomic testing could support more efficient use of resources, particularly in Asia where cancer care demand is rising. The key challenge will be ensuring that precision medicine does not become available only to those who can afford it, but is gradually integrated into broader, evidence-based cancer care.
