A new study indicates that an important drug used to treat breast cancer is just as effective when the course of treatment is shortened by half.
Herceptin, also known as trastuzumab, is used to treat human epidermal growth factor receptor 2 (HER2) positive breast cancer. This particularly aggressive form of breast cancer expresses a high level of HER2 protein, which promotes the division and growth of cells.
The PERSEPHONE study, carried out by researchers at the University of Cambridge, found that Herceptin treatment in patients with early-stage breast cancer is just as effective when taken for six months as when taken for a full year.
Professor Helena Earl, chief investigator of the study, said: 'We are confident that this will mark the first steps towards a reduction in treatment duration for many women with HER2-positive breast cancer.'
Determining the optimum treatment duration is important because of Herceptin's serious side effects. Herceptin has high toxicity within the body, which worsens with increased use and can result in permanent damage, such as congestive heart failure or stroke.
The phase III randomised trial enrolled 4089 women aged between 23 and 82 years with HER2 positive breast cancer and followed them for a median of 4.9 years after treatment. The results demonstrated that there was no significant difference in disease-free survival at four years: 89 percent in both groups.
Adverse effects were significantly different between the groups, however. Only 4 percent of patients in the six months treatment group forced to stop taking the drug due to cardiotoxicity, compared with 8 percent in the 12 months group.
'I have personally seen congestive heart failure caused by Herceptin,' Dr Otis Brawley, chief medical and scientific officer of the American Cancer Society, told The New York Times. 'The longer you give it, the likelier they are to get it. So it's a wonderful thing if you can give it for a shorter time.'
The data is currently unpublished but it is due to be presented for the first time at the American Society of Clinical Oncology annual meeting in June 2018.