Genomic Test Enables Millions of Breast Cancer Patients to Safely Skip Chemotherapy, Trial Shows

The Optima trial, an international, randomized study led by University College London, evaluated whether the Prosigna genomic test could identify early-stage, hormone-positive breast-cancer patients who would not benefit from chemotherapy. Researchers enrolled 4,429 participants aged 40 or older from the United Kingdom, Norway, Sweden, Australia, New Zealand and Thailand. Patients were assigned either to standard care (chemotherapy followed by hormone therapy) or to a test-guided arm in which Prosigna scores dictated treatment: high-score patients received both therapies, low-score patients received hormone therapy alone.

The Guardian

Prosigna, developed by diagnostics firm Veracyte, analyses the activity of 50 genes in tumour tissue to assign a molecular subtype and a “Risk of Recurrence in the Next 10 Years” score. The trial’s funding came from the National Institute for Health and Care Research (NIHR), Veracyte and several cancer charities.

Reuters

Five-year cancer-free survival was 93.7 % in the test-guided, chemotherapy-omitted group and 94.9 % in the standard-care group, a statistically non-inferior difference reported by Reuters. The Guardian’s coverage cited 95 % versus 94 % survival for the same arms, reflecting minor reporting variations. In both datasets, patients with low Prosigna scores showed no meaningful advantage from chemotherapy, indicating that omission does not increase recurrence risk for this cohort.

The Guardian

Karen Bonham, a 55-year-old speech-language therapist from Wales, was allocated to the low-score arm. She described the notification as “immense relief? Like Christmas? Certainly a mixture of the two.” After completing radiotherapy and hormone therapy, Bonham remains cancer-free nine years post-diagnosis and attributes her quality of life to the test-guided decision.

The Guardian

Prof. Rob Stein, chief investigator and professor of breast oncology at UCL, emphasized that the trial “addresses a longstanding challenge in breast cancer care: identifying who truly benefits from chemotherapy and who does not.” Prof. Iain MacPherson, co-chief investigator at the University of Glasgow, called the evidence “robust, practice-changing” for hormone-sensitive disease. Dr. Kelly Marcom, Veracyte’s medical director for breast cancer, described the results as “a major milestone in precision breast oncology” with the potential to transform treatment selection.

The Guardian

The trial included too few male participants to draw firm conclusions for men, a limitation noted by investigators. Additionally, the study’s age threshold and focus on hormone-positive tumours leave the applicability of Prosigna to younger patients or other subtypes untested. The slight discrepancy in reported survival percentages highlights the need for consistent data presentation.

The Guardian

Findings will be presented at the American Society of Clinical Oncology meeting in Chicago. If incorporated into clinical guidelines, the Prosigna test could reduce chemotherapy use for a substantial proportion of breast-cancer patients, easing treatment-related toxicity and lowering health-system costs. Ongoing follow-up will assess long-term outcomes and broader population applicability.

The Guardian

• “Prof Rob Stein, the trial’s chief investigator and a professor of breast oncology at UCL, said: “Optima addresses a longstanding challenge in breast cancer care: identifying who truly benefits from chemotherapy and who does not.” — Prof. Rob Stein, Professor of Breast Oncology, UCL

The Guardian

• “Prof Iain MacPherson, a co-chief investigator and professor of breast oncology at the University of Glasgow, said: “Optima provides robust, practice-changing evidence that we can safely reduce the use of chemotherapy for many patients with hormone-sensitive breast cancer.” — Prof. Iain MacPherson, Professor of Breast Oncology, University of Glasgow

The Guardian

• “represent a major milestone in precision breast oncology.” — Dr. Kelly Marcom, Medical Director for Breast Cancer, Veracyte

Reuters

• “How to describe the initial feeling? Immense relief? Like Christmas? Certainly a mixture of the two,” — Karen Bonham, trial participant

The Guardian

• “I hope that the trial will bring positive patient outcomes to many.” — Karen Bonham, trial participant

The Guardian