On Saturday in Chicago, researchers will present findings that could reshape breast cancer care for millions of women: a genomic test that identifies who can safely skip chemotherapy without compromising their survival. The Optima trial, led by University College London and involving 4,429 patients across six countries, demonstrates that many women with hormone-positive breast cancer—the most common form, accounting for up to 80% of all breast cancer cases globally—can avoid the toxic side-effects of chemotherapy altogether.
For decades, breast cancer patients have faced an agonising trade-off. After surgery to remove tumours, chemotherapy has been routinely recommended to reduce the risk of recurrence. Yet the treatment exacts a punishing physical and emotional toll: hair loss, rashes, nausea, insomnia, and fatigue are common, while some women suffer life-changing consequences including infertility, cognitive impairment, or early menopause. Now the Prosigna test, made by diagnostics company Veracyte, offers a way forward by analysing the activity of 50 genes in tumour tissue to calculate an individual's risk of cancer returning within the next decade.
The trial's design was elegantly simple. Patients aged 40 and over with hormone-positive breast cancer in the UK, Norway, Sweden, Australia, New Zealand, and Thailand were divided into two groups. The standard-care group received chemotherapy followed by hormone therapy. The second group had their tumours analysed with the genomic test: those with high scores received both treatments, while those with low scores received hormone therapy alone. Five years after treatment, the results were striking. Among those who had skipped chemotherapy based on low test scores, 94% were alive and free from cancer recurrence—nearly identical to the 95% survival rate in those who had received chemotherapy. For patients with low scores, the test revealed, chemotherapy offered little or no additional benefit.
One trial participant described the experience as feeling "like Christmas," and now, nine years after her diagnosis and decision to forgo chemotherapy, she remains healthy and enjoying a full and active life. Prof Rob Stein, the trial's chief investigator and professor of breast oncology at UCL, emphasised the broader significance: "Our findings show that many patients can safely avoid chemotherapy without compromising their outcomes. This marks an important and significant step toward more personalised treatment."
The implications extend beyond individual patients. By sparing women unnecessary chemotherapy, health systems can redirect resources more efficiently and evidence-based way. Prof Iain MacPherson, co-chief investigator at the University of Glasgow, called the findings "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 Optima trial was funded by the National Institute for Health and Care Research, Veracyte, and cancer charities. While some men participated in the study, there were too few to draw firm conclusions for this group. As these findings ripple through international healthcare systems, they signal a fundamental shift: from one-size-fits-all cancer treatment to care tailored to individual tumour biology—sparing millions from suffering without sacrificing their chance at survival.