en.Wedoany.com Reported - A major international clinical trial led by University College London (UCL) has found that genetic testing can help many breast cancer patients safely avoid chemotherapy, sparing them from unnecessary side effects without affecting the risk of cancer recurrence.
The OPTIMA trial (Optimal Personalized Treatment of early breast cancer using Multi-parameter Analysis) aims to reduce unnecessary chemotherapy in newly diagnosed breast cancer patients. The trial tracked over 4,400 patients from the UK, Norway, Sweden, Australia, New Zealand, and Thailand.
Results presented at the 2026 American Society of Clinical Oncology (ASCO) meeting in Chicago showed that patients aged 40 and over with low Prosigna test scores could receive hormone therapy alone, potentially changing treatment for thousands of patients each year.
For early-stage breast cancer patients whose cancer has spread from the breast to nearby lymph nodes, chemotherapy is typically offered to reduce the risk of recurrence. Although chemotherapy is generally effective, clinicians are concerned that many patients with the most common hormone-sensitive breast cancer derive little or no benefit from chemotherapy while still experiencing significant and sometimes dangerous side effects.
OPTIMA addresses this challenge by using Veracyte's Prosigna genomic test. This test measures the activity of genes involved in breast cancer growth. Unlike some similar tests, Prosigna can be performed by NHS laboratories equipped with the necessary facilities. The test is conducted on cancer tissue samples, usually from surgically removed tumors, but because the test uses very little tissue, it can also be performed on diagnostic needle biopsy samples.
Professor Rob Stein, Chief Investigator of the OPTIMA trial and Professor of Breast Oncology at the UCL Cancer Institute, said the trial addresses a long-standing challenge in breast cancer treatment: determining who truly benefits from chemotherapy. The results show that many patients can safely avoid chemotherapy without compromising treatment outcomes, marking a significant step toward more personalized treatment. The trial uses tumor biology to guide decisions rather than relying solely on traditional clinical features. For patients, many may be spared the physical and emotional burden of chemotherapy and its potential long-term side effects; for healthcare systems, it represents a more efficient and evidence-based use of resources.
The OPTIMA trial enrolled men and women aged 40 and over who had surgery for hormone-sensitive breast cancer. Most patients had cancer that had spread to lymph nodes under the arm, placing them at high risk of future recurrence. Standard treatment includes chemotherapy followed by standard hormone pills taken for five to ten years.
Participants were randomly assigned to two groups. The standard treatment group received chemotherapy followed by hormone therapy. The test-directed group had their tumors tested using Prosigna; patients with high scores (above 60) received chemotherapy and hormone therapy, while those with low scores (60 or less) received hormone therapy alone. Both groups received radiotherapy and other treatments as usual.
The trial assessed whether test-directed treatment would or would not lead to a meaningful increase in cancer recurrence or death within five years. After consultation with patients and clinicians, researchers defined an acceptable difference as no more than 3%.
Of the 4,429 people in the trial, more than two-thirds (68%) had low Prosigna scores. Results showed very similar outcomes regardless of whether chemotherapy was received. Five years after treatment, 94.8% of patients who received chemotherapy plus hormone therapy were alive without breast cancer recurrence, compared to 93.6% of those who received hormone therapy alone. A statistical test showed that among patients with low Prosigna scores, at most only 2% would benefit from chemotherapy. This indicates that chemotherapy provides little or no additional benefit for patients with low Prosigna scores.
Overall, the findings suggest that using the Prosigna test to guide treatment decisions can help a large number of patients avoid unnecessary chemotherapy without affecting outcomes. Researchers estimate that as a result of this trial, more than 5,000 NHS patients per year could avoid chemotherapy.
Results from the full trial population will be used to inform decision-making by healthcare bodies such as the National Institute for Health and Care Excellence (NICE), demonstrating that test-directed treatment is cost-effective and making the Prosigna test more widely available in the NHS. The results showed similarly high survival rates but reflected a broader mix of patients, including those at higher risk of recurrence.
The research team also examined whether outcomes differed in specific patient groups. Results were similar for premenopausal and postmenopausal women, and no differences were observed based on the number of affected lymph nodes, including patients with cancer spread to more than three nodes. Some men did participate in the study, but the numbers were too small to draw definitive conclusions for this group.
The results indicate that patients aged 40 and over with hormone-sensitive breast cancer and low Prosigna scores can safely avoid chemotherapy. Unlike previous studies that mainly focused on postmenopausal women with limited lymph node involvement, OPTIMA included premenopausal women and patients with more extensive disease. Premenopausal women in the trial received hormone therapy that temporarily suppressed ovarian function, which researchers believe explains why chemotherapy appeared to offer no additional benefit in this group. The research team cautioned that it is not yet clear whether these findings apply to patients under 40. The next phase of OPTIMA aims to provide more information on test use in premenopausal women, but results are still several years away.
Co-Chief Investigator Professor Iain MacPherson, Professor of Breast Oncology at the University of Glasgow, said OPTIMA provides strong, practice-changing evidence that chemotherapy use can be safely reduced for many patients with hormone-sensitive breast cancer. These findings mark a significant step toward delivering more personalized, precise care, ensuring that treatment decisions are driven by factors that truly improve patient outcomes while avoiding unnecessary toxicity.
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