Using Herceptin together with another powerful breast cancer drug before surgery could shrink or destroy tumours in just 11 days, a study has found.

Some patients may be spared chemotherapy if they are given a combination of the drugs Tyverb (lapatinib) and Herceptin (trastuzumab) immediately after diagnosis, according to the research by a team of British doctors.

The medics, who presented their study to experts at the European Breast Cancer Conference in Amsterdam, said their findings had “groundbreaking potential”.

Some 257 women with an aggressive form of cancer – HER2 – were involved in the clinical trial and either received no treatment, one of the drugs or a combination of them.

Around a quarter of the women on the combined treatment saw their tumours shrink or disappear.

Trial co-leader Professor Judith Bliss, from the Institute of Cancer Research in London, said it was “unexpected to see quite such dramatic responses to the trastuzumab and lapatinib within 11 days”.

She added: “Our results are a strong foundation on which to build further trials of combination anti-HER2 therapies prior to surgery – which could reduce the number of women who require subsequent chemotherapy, which is also very effective but can lead to long-term side effects.”

At present, women usually have their tumour removed during surgery followed by a combination of chemotherapy, radiotherapy, hormonal therapies and targeted drugs such as Herceptin.

Professor Arnie Purushotham, senior clinical adviser at Cancer Research UK, which funded the study, said: “These results are very promising if they stand up in the long run and could be the starting step of finding a new way to treat HER2 positive breast cancers.”

Around 5,300 to 8,000 women a year are diagnosed with HER2 positive breast cancer.