DNA Test Allows Breast Cancer Patients to Avoid Chemotherapy

Kathmandu. A patient undergoing a mammogram at a modern medical facility is being assisted by a nurse. The patient is wearing a medical gown, and the nurse is wearing a dark blue top and white gloves.

There is a possibility that millions of breast cancer patients can now safely avoid chemotherapy. This conclusion has been reached because a DNA test developed by scientists can distinguish which patients will benefit from treatment and which will not, trial results have shown.

An international study has shown that more than two-thirds of patients in the trial can be spared the side effects of chemotherapy and can be treated with hormone therapy alone.

Chemotherapy can cause fatigue, vomiting, hair loss, weakened immune system, and fertility problems.

This study was led by University College London. It involved more than 4,000 newly diagnosed patients over the age of 40 from the UK, Norway, Sweden, Australia, New Zealand, and Thailand.

Scientists used a gene test called 'Prosigna' to measure the activity of 50 genes involved in breast cancer growth to calculate the risk of the disease returning.

Patients with a low score (i.e., two-thirds of the group) were not given chemotherapy. Their five-year survival rate was 93.7 percent, while the survival rate for patients who received chemotherapy was 94.9 percent.

The main treatment for breast cancer is usually surgery to remove the tumor. Chemotherapy is often recommended afterward to reduce the risk of the disease returning.

This treatment is also regularly given to patients with early-stage breast cancer that has spread to nearby lymph nodes.

According to UCL, doctors are concerned that this treatment offers very little benefit to patients with the most common types of breast cancer. According to the university, the trial results mean that more than 5,000 NHS patients each year could avoid chemotherapy.

Karin Bonham from Cardiff was a participant in the trial. She said the results were a 'huge relief' and 'felt like Christmas'.

Bonham, 64, avoided chemotherapy due to the 'Prosigna' test and received radiotherapy and hormone therapy for eight years. 'A cancer diagnosis and treatment can be very shocking,' she said.

'It throws you into a world of uncertainty. Life priorities change, you just want to survive.' 

The findings of this study will be presented at the world's largest cancer conference, the American Society of Clinical Oncology's annual meeting, in Chicago, USA, on Saturday.

A leading cancer specialist, David Miles, described these findings as 'game-changing for medical practice'. He told the BBC, 'We can now say with confidence that many patients do not benefit from chemotherapy, so there is no need to give them this treatment.'

He added, 'This test enables doctors to identify a large group of women who do not really benefit, and who do not have to suffer unnecessarily.'

'Previously, we would give chemotherapy to 100 women, of whom only 10 would benefit, but 90 would not need it at all,' he said.

Tanya Hutson, diagnosed with breast cancer in 2022, called the new DNA test 'absolutely wonderful'. 'It proves what happens when research is funded,' she said, adding that chemotherapy was 'extremely harsh'.

'For those who don't need it but are given it, this achievement will surely make a difference.'

According to UCL, it is not yet known whether these findings apply to people under 40, and it will take a few more years for the results to come in.

Alicia Curry/BBC