Every year in the United Kingdom, there are over 400,000 new cases of cancer, with more than 59,000 of these new cases being attributable to breast cancer, as reported by Cancer Research UK. Despite also affecting a small proportion of men, breast cancer is overall the most common cancer in women, affecting around one in seven women in the UK during their life. In addition to its high nationwide prevalence, breast cancer is a leading medical concern internationally, and according to the World Health Organisation (WHO), there were approximately 2.3 million women around the world diagnosed with breast cancer in 2022, emphasising the urgent need for improved patient care.
Women with breast cancer are typically treated with surgery, chemotherapy, or both, and chemotherapy in particular is commonly used in conjunction with hormone therapy to prevent the recurrence of early-stage breast cancer that has spread to the lymph nodes. However, in recent years, there has been a growing uncertainty in the scientific community as to whether chemotherapy yields any positive outcomes for patients with the most prevalent type of breast cancer, hormone-sensitive breast cancer, in spite of its unpleasant and potentially life-altering side effects, including hair loss, immunosuppression, and even impaired cognition and infertility. This uncertainty has created an immense problem for clinicians, as it makes it difficult to determine which patients will truly be helped by chemotherapy and which ones can simply go without.
To address this issue, researchers from University College London led an international clinical trial called OPTIMA. The trial enrolled over 4,400 men and women aged 40 or older from the UK, New Zealand, Australia, Norway, Sweden, and Thailand, who were diagnosed with hormone-sensitive breast cancer and had undergone surgery. The majority of individuals comprising the patient cohort had their cancer metastasise to adjacent lymph nodes, making them more vulnerable to having their cancer recur.
The trial divided participants into two separate groups, which were then compared. The first group received conventional treatment involving chemotherapy and hormone therapy, while the second group had their tumour analysed using Prosigna, a genomic test that can determine the risk of the breast cancer returning within ten years. The test, developed by the diagnostics company Veracyte, measures the expression of 50 genes in tumour tissue and allocates a Risk of Recurrence (ROR) score of 0-100, with a score of 100 indicating the highest risk of recurrence. Individuals in the second group who scored higher than 60 were treated with chemotherapy and hormone therapy, while those with a Prosigna score of 60 or lower were treated only with hormone therapy.
The results of the trial, presented a month ago at the 2026 American Society of Clinical Oncology (ASCO) meeting, indicated that five years following treatment, patients with a low Prosigna score had a similar survival and recurrence rate to patients who were treated with chemotherapy, despite not being treated with chemotherapy themselves. These results suggested that patients with a low Prosigna score can safely forgo chemotherapy treatment without compromising their prognosis.
The OPTIMA trial represents a remarkable milestone in personalised medicine, and it has even been predicted that over 5,000 NHS patients per year could avoid experiencing the physiological and psychological load of chemotherapy due to its findings. The trial included premenopausal women and patients with more advanced disease, making it different from preceding studies. However, despite the success of the trial, it is currently unknown whether its findings are relevant for patients younger than 40 years old. Additionally, men represented a small fraction of the participants, and consequently, the applicability of the obtained results to this subgroup remains unclear.
Yet, with the current number of breast cancer cases remaining high, the results of the OPTIMA trial become even more significant. The trial could potentially open the doors for further research exploring the efficacy of the Prosigna test in other contexts. Over time, more breast cancer patients may benefit from such personalised treatments, improving their quality of life while reducing nonessential chemotherapy exposure.
