MANCHESTER, England, March 10 (UPI) -- Researchers in England report a two-drug combination given to patients ahead of surgery to remove breast cancer shrank tumors significantly, if they did not disappear, in 11 days.
Patients diagnosed with a specific form of breast cancer, human epidermal growth factor receptor 2, or HER2, positive, saw their tumors shrink or disappear after being given lapatinib and trastuzumab after diagnosis and before other treatments, but researchers say more trials are needed to confirm what they have called "mind-blowing" results.
The treatment was so successful, the researchers changed the study as early data was reported, shifting halfway through the study from testing the drugs separately to testing them together across the entire group of participants.
"For solid tumours to disappear in 11 days is unheard of," Nigel Bundred, a professor of surgical oncology at the University of Manchester, told the Telegraph. "These are mind-boggling results."
Researchers said the results of combining the targeted cancer drugs may help shift toward more specific treatment -- the drugs were effective against a specific type of tumor -- allowing for new ideas on how to attack the disease.
"This has ground-breaking potential because it allows us to identify a group of patients who, within 11 days, have had their tumors disappear with anti-HER2 therapy alone and who potentially may not require subsequent chemotherapy," Budred said in a press release. "This offers the opportunity to tailor treatment for each individual woman."
For the study, presented at the European Breast Cancer Conference, researchers recruited 257 women in England with operable HER2-positive breast cancer between November 2010 and September 2015 to be treated either with trastuzumab, lapatinib or nothing for 11 days after diagnosis but before surgery in a two-part trial.
Data on 130 women included in part one showed the combination of drugs was so effective against cancer that researchers changed the second part of the trial, giving the 127 women in the second group either trastuzumab, both drugs or nothing. In both parts, women received standard care before and after surgery.
The researchers report cancer completely disappeared in 11 percent of the women, and an additional 17 percent saw tumors shrink to smaller than five millimeters.
More research is needed to repeat the trial's results, but the researchers said the treatment could be effective for the more aggressive HER2-positive tumors, as well as lead more personalized cancer treatment.
"We hope this particularly impressive combination trial will serve as a stepping stone to an era of more personalized treatment for HER2 positive breast cancer," Delyth Morgan, chief executive of Breast Cancer Now, told the BBC. "Such a rapid response to treatment could soon give doctors the unprecedented ability to identify women responding so well that they would not need grueling chemotherapy."