One year of therapy is just right.
Administering one year of trastazumab (Herceptin) has long been the standard for patients with human epidermal receptor 2 (HER2) – positive, early stage breast cancer. Patients often ask me why we use this length of treatment, and my answer has been less than satisfactory: The length is not based on a clear scientific rationale, but rater was agreed upon by committee members who designed the first adjuvant (in addition to surgery) clinical trials of the drug.
The initial reports of the phase III, international, randomized HERA trial (Lancet 2007;369:29) showed that one year of trastazumab after standard neoadjuvant (before surgery) or adjuvant (after surgery) chemotherapy led to a significant improvement in overall survival versus observation (after chemotherapy) for those with early, HER2-positive invasive breast cancer. Subsequent data suggested that 6 months of adjuvant trastuzumab may not be inferior to 1 year of therapy.
The next question is whether longer duration Herceptin might be better than shorter. The HERA trial investigators compared the effectiveness of 2 years versus 1 year of adjuvant Herceptin. At a median follow-up of 8 years, there was no advantage to the longer length treatment, as compared to 1 year. However, the risk of more serious complications (grade 3 or 4 adverse events) were more common in the 2-year treatment group (20.4% versus 16.3%), as were decreases in heart function (left ventricular ejection fraction decreases in 7.2% versus 4.1%).
Summary: Although the original 1 year duration of trastuzumab (Herceptin) was selected somewhat arbitrarily, trial results have not suggested any advantage to the use of shorter or longer duration regimens. The standard of care remains adjuvant trastuzumab (Herceptin) for 1 year. I’m Dr. Michael Hunter.
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References: Goldhirsch A et al. 2 years versus 1 year of adjuvant trastuzumab for HER2-positive breast cancer (HERA): An open-label, randomized controlled trial. Lancet 2013 July 18; Joensuu H. Duration of adjuvant trastuzumab: Shorter beats longer. Lancet 2013 Jul 18.