This summary table contains detailed information about research studies. Summary tables offer an informative look at the science behind many breast cancer guidelines and recommendations. However, they should be viewed with some caution. In order to read and interpret research tables successfully, it is important to understand some key concepts. Learn how to read a research table.
Introduction: About 20 percent of breast cancers have high amounts of a protein called HER2 on the surface of the cancer cells (called HER2-positive breast cancer or HER2 over-expression) [1-2]. The drug trastuzumab (Herceptin) targets HER2-positive cancer cells. When attached to the HER2 protein, trastuzumab can slow or stop the growth of the cancer cells.
Learn more about HER2 status.
Studies show that chemotherapy plus trastuzumab increases overall survival compared to chemotherapy alone in women with HER2-positive early breast cancer (see table below).
Trastuzumab also improves survival for people with HER2-positive metastatic breast cancer (see Table 50).
Learn more about trastuzumab (Herceptin).
Learn more about the health risks of trastuzumab.
Learn about the strengths and weaknesses of different types of studies.
Study selection criteria: Phase III clinical trials with 100 or more participants and meta-analyses.
Study Population(number of participants)
Percent Surviving—Chemotherapy plus Trastuzumab
Percent Surviving—Chemotherapy Alone(no Trastuzumab)
Absolute Improvement in Overall Survival with the Addition of Trastuzumab to Chemotherapy
Phase III clinical trials
NSABP and NCCTG trials 
HERA Study 
Breast Cancer International Research Group 
Spielmann et al. 
FinHer Study 
Dahabreh et al. 
Moja et al. 
Viani et al. 
O’Sullivan et al. 
Sig = Statistically significant improvement compared to standard treatment alone NS = No statistically significant difference between the two treatment groups *About 2 years of follow-up for each study in the meta-analysis
† All women had hormone receptor-negative tumors two centimeters (2 cm) or smaller. Among 2,263 women with hormone receptor-positive tumors 2 cm or smaller who got hormone therapy instead of chemotherapy, trastuzumab also significantly improved survival.
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