Many people with breast cancer can safely avoid chemotherapy with the use of a gene test, potentially sparing them unnecessary side effects without increasing the risk of the cancer returning, a large international clinical trial which The Christie NHS Foundation Trust was involved with has found.
The OPTIMA trial (Optimal Personalised Treatment of early breast cancer using Multi-parameter Analysis) was designed to reduce the use of unnecessary chemotherapy for people with newly diagnosed breast cancer. It followed more than 4,400 patients across the UK, Norway, Sweden, Australia, New Zealand and Thailand.
The findings, which were presented at the 2026 American Society of Clinical Oncology (ASCO) meeting in Chicago at the end of May, suggest that people aged 40 and over whose tumours have a low Prosigna test score can be treated safely with hormone therapy alone, potentially transforming care for thousands of patients each year.
Chemotherapy is regularly offered to people with early‑stage breast cancer that has spread from the breast to nearby lymph nodes, as it lowers the risk of the disease returning. While effective overall, there is concern among clinicians that many people with the most common, hormone‑sensitive type of breast cancer receive little or no benefit from chemotherapy but still experience its significant and sometimes dangerous side effects.
OPTIMA set out to address this dilemma by using a genomic test from Veracyte called Prosigna, which measures the activity of genes involved in breast cancer growth. Unlike some similar tests, Prosigna can be run by NHS laboratories with the appropriate equipment.
The test is performed on cancer tissue samples. Typically, these are tumours removed at surgery but as the test uses very little tissue, it also works on diagnostic needle biopsies.
Dr Anne Armstrong, Consultant Medical Oncologist, who is leading on the trial at The Christie, says: “To have a test that can tell us who can be spared chemotherapy is very exciting. Although it can’t help all breast cancer patients, it will hopefully be approved on the NHS and would be beneficial to patients like Aileen with the hormone-driven type of the disease. If the Prosigna test was approved to be routinely used, it may be able to reduce the use of chemotherapy without having any effect on rates of successful treatment.
“This is another example of how we’re moving towards more targeted and personalised treatments, meaning patients aren’t unnecessarily exposed to the toxicity of chemotherapy.”
The OPTIMA trial recruited women and men aged 40 or older following surgery for hormone-sensitive breast cancer. Most had their cancer spread to under arm lymph nodes which placed them at high risk of future recurrence. Because of this, their usual treatment included both a course of chemotherapy and standard hormone tablets taken for five to ten years.
Participants were randomly assigned to one of two groups:
- Standard treatment group: patients received chemotherapy followed by hormone therapy.
- Test‑directed group: patients had their tumour tested using Prosigna. Those with a high score (above 60) received chemotherapy and hormone therapy, while those with a low score (less than or equal to 60) were treated with hormone therapy alone.
Radiotherapy and other treatments were given as usual in both groups.
The trial was designed to assess whether test‑directed treatment would or would not lead to a meaningful increase in the number of people whose cancer returned or who died within five years. In consultation with patients and clinicians, the researchers defined an acceptable difference as no more than 3%.
Key findings
Of the 4,429 people who took part in the trial, more than 2 thirds (68%) had a low Prosigna score.
For this group, the results showed that outcomes were very similar whether chemotherapy was given or not. 5 years after treatment:
- 8% of those who received chemotherapy alongside hormone therapy were alive and free from breast cancer recurrence
- 6% of those treated with hormone therapy alone were also alive and recurrence-free
A statistical test showed that at the most, only 2% of patients with a low Prosigna score treated with chemotherapy will benefit from this treatment.
This suggests that for patients with low Prosigna scores, chemotherapy offers little or no additional benefit, meaning many people could safely avoid it and its side effects.
Overall, the findings indicate that using the Prosigna test to guide treatment decisions could help a substantial number of patients avoid unnecessary chemotherapy without compromising their outcomes. Researchers estimate more than 5000 NHS patients a year could avoid chemotherapy because of this trial.
Results for 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), about wider NHS access to Prosigna testing, by demonstrating that test‑directed treatment is cost‑effective. The results also show similarly high survival rates, but reflect a broader mix of patients, including those at higher risk of recurrence.
Patient’s story
Aileen Pritchard is 65 and lives in Darwen, Lancashire, with her husband Kevin. She has 3 daughters.
She was diagnosed with stage 3 breast cancer in 2018 and, thanks to the OPTIMA trial, didn’t have to have any chemotherapy as part of her treatment.
Kevin and Aileen own their own business – a dry cleaners called Smart Alex. They work 6 days a week and would have struggled to keep it going if Aileen had had to have chemotherapy.
She had a mastectomy and hormone therapy and is still cancer free nearly 8 years on.
Reflecting on her experience of the trial, Aileen says: “If I had to have chemotherapy, I probably would have had to stop working and we might have lost our livelihood, which would have been disastrous. I can still picture where I was and how I felt when the nurse told me the news – I could almost feel the weight lifting off my shoulders. It was a huge relief.
“Being able to live the best life possible during cancer treatment is so important for both your physical and mental health. I was able to do all the things I love, like going swimming three to four times a week and getting away for the weekend with Kevin.
“It’s great that the results show that this test works, and I hope that more people will be able to benefit from it in the future. I had no reservations about joining the trial. Science and medicine can’t advance without research, so I was glad to play my part in helping people like me in the future.”