A trial of more than 10,000 women with the most common form of early breast cancer found the treatment was unnecessary for many after surgery.
The findings will lead to a “fundamental change” in how the disease is treated, a leading oncologist said. An estimated 3,000 to 5,000 of women in the UK are likely to avoid chemotherapy every year as a result.
More than 20,000 women in the UK are diagnosed with hormone-receptor positive, HER2-negative, node-negative breast cancer annually.
Around half of these patients would historically receive chemotherapy after having surgery to remove their tumour to prevent recurrence of the disease.
However, the results of the TAILORx trial show only 30 per cent of women with this particular form of early-stage breast cancer benefit from the treatment.
A leading Scottish breast cancer charity described the findings as “incredible” and “game-changing”.
The study is thought to be the largest breast cancer treatment trial ever conducted. Dr Alistair Ring, consultant medical oncologist at the Royal Marsden NHS Hospital in London, said: “I think this is a fundamental change in the way we treat women with early-stage breast cancer and will lead to a considerable number of women no longer needing to have chemotherapy.”
The TAILORx trial used the Oncotype DX test, which is available on the NHS and which allows doctors to predict the likelihood of the breast cancer returning.
A sample of the tumour is tested after surgery for 21 genetic markers, which indicate if it could grow and spread.
Patients with a recurrence score of up to ten out of 100 have previously been shown not to benefit from chemotherapy and need only hormone treatment. Those who score 26 or higher on the scale do benefit and currently receive chemotherapy.
However, there was unclear evidence on whether those who fall in between – the vast majority of patients – needed chemotherapy.
The TAILORx study, led by the Montefiore Medical Centre in New York, found women older than 50 with this form of breast cancer and a score of up to 25 did not need chemotherapy. Under-50s with a score of up to 15 can also be spared the treatment.
Angela Harris, head of Scotland at Breast Cancer Care, said: “This incredible news is game-changing as it means thousands of women in Scotland and across the UK will be able to avoid chemotherapy with confidence. Whether or not to have the treatment is a terrible dilemma for many women with certain types of breast cancer as they often don’t have clear-cut answers on the benefits. Devastating side effects such as hair loss, severe pain and infertility can be traumatic and life-changing, yet many endure it to try and avoid the cancer coming back.”
She added: “We hope to see NHS Scotland adopt this practice as soon as possible.”
Nina Barough, the founder and chief executive of Walk the Walk – the breast cancer charity behind the coming Moonwalk Scotland event – said: “I had my cancer 20 years ago and, at that time, scientists knew chemotherapy wasn’t suitable for everybody, but what they couldn’t tell is who it was suited for and who it wasn’t.
“Breast cancer treatments have advanced so much that treatments can almost be tailored for patients and this is extremely welcome news as chemotherapy is a particularly invasive treatment.”
Baroness Delyth Morgan, chief executive of Breast Cancer Now, said: “It’s fantastic news this landmark study could enable thousands more breast cancer patients over 50 to be safely spared gruelling chemotherapy.
“This is another significant step towards personalised breast cancer treatment and we hope these practice-changing findings will help refine our use of chemotherapy on the NHS.”