Millions of women with breast cancer could be spared chemo with genomic test

A genomic test may help some women with breast cancer avoid chemotherapy, with near-identical outcomes in an international trial.

The findings suggest patients with a low test score could be treated with hormone therapy alone without increasing the risk of their cancer returning.

Researchers said the results could support more personalised treatment decisions and spare some women the side-effects of chemotherapy.

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.

“Our findings show that many patients can safely avoid chemotherapy without compromising their outcomes.

“These results mark an important and significant step toward more personalised treatment.

“The trial has successfully used tumour biology to guide decisions rather than relying solely on traditional clinical features.”

Breast cancer treatment usually involves surgery to remove tumours. Chemotherapy is then often recommended if doctors believe there is a risk the disease will return.

Chemotherapy can cause side-effects including hair loss, rashes, nausea, insomnia and fatigue. Some women may also face longer-term consequences such as infertility, cognitive impairment or early menopause.

The Optima trial followed more than 4,000 patients with newly diagnosed breast cancer in the UK, Norway, Sweden, Australia, New Zealand and Thailand.

The trial was led by University College London.

One woman who took part in the trial told the Guardian that being able to skip chemotherapy felt “like Christmas”. Nine years after being diagnosed, taking the test and skipping chemotherapy, she is healthy and enjoying a full and active life.

The trial tested whether a genomic test could identify which patients need chemotherapy and which could safely avoid it.

The Prosigna test, made by diagnostics company Veracyte, analyses the activity of 50 genes in tumour tissue. It identifies the molecular subtype of the cancer and gives a score estimating the risk of breast cancer returning in the next 10 years.

The randomised trial involved 4,429 patients aged 40 or over with hormone-positive breast cancer. Hormone-positive breast cancer grows in response to hormones such as oestrogen or progesterone. It is the most common form of breast cancer, accounting for up to 80 per cent of cases globally.

Participants were assigned to one of two groups. In the standard treatment group, patients received chemotherapy followed by hormone therapy.

In the second group, patients had their tumours analysed using the genomic test. Those with a high score received chemotherapy and hormone therapy. Those with a low score received hormone therapy alone.

Radiotherapy and other treatments were given as usual in both groups.

In the second group, outcomes were very similar whether chemotherapy was given or not. Five years after treatment, 95 per cent of patients who had chemotherapy and hormone therapy were alive and free from breast cancer recurrence, while 94 per cent of those who skipped chemotherapy were also alive and recurrence-free.

The findings suggest chemotherapy offered little or no additional benefit for patients with low test scores.

Some men also took part in the study, but researchers said there were too few to draw firm conclusions for this group.

The trial received funding from the National Institute for Health and Care Research, Veracyte and cancer charities.

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.

“These findings represent 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 potential impact for both patients and health services is substantial.”