The combination of two powerful breast cancer drugs could dramatically shrink or destroy tumours in just 11 days, doctors in the UK had found.
Some patients with HER2 positive breast cancer may not need chemotherapy if they were given the drugs straight after diagnosis and before they had surgery.
Around 15 per cent to 25 per cent of women diagnosed with breast cancer had HER2, which tended to grow faster than some other types of breast cancer.
Researchers had discovered that administering a combination of the drugs Tyverb (lapatinib) and Herceptin (trastuzumab) to women before surgery could lead to significant shrinking or complete disappearance of the tumours.
The results were observed even in some of the women who had cancer that had already spread to their lymph nodes.
The findings were presented at the European Breast Cancer Conference in Amsterdam, which experts described as exciting.
According to professor Nigel Bundred, from the University of Manchester and the University Hospital of South Manchester NHS Foundation Trust, who presented the data, "This has groundbreaking potential because it allows us to identify a group of patients who, within 11 days, have had their tumours disappear with anti-HER2 therapy alone and who potentially may not require subsequent chemotherapy.
The combination of drugs had worked in about about 25 per cent of the 66 women who were treated for 11 days.
Samia al Qadhi, chief executive at Breast Cancer Care, said, ''The astonishing findings in this study show that combining these two drugs has the potential to shrink HER2 positive breast cancer in just 11 days.
''For some HER2 positive breast cancer patients the effect of this drug combination will be amazing and mean they can avoid chemotherapy and its gruelling side effects completely. For others, their tumours may not shrink, but doctors will know either way very quickly, giving them the ability to rapidly decide on further treatment.