This summary table contains detailed information about research studies. Summary tables are a useful way to look at the science behind many breast cancer guidelines and recommendations. However, to get the most out of the tables, it’s important to understand some key concepts. Learn how to read a research table.
Introduction: About 10-20 percent of newly diagnosed breast cancers are HER2-positive [1-2]. This means they have high amounts of a protein called HER2 on the surface of the cancer cells.
The drug trastuzumab (Herceptin) targets HER2-positive cancer cells. Chemotherapy plus trastuzumab increases overall survival compared to chemotherapy alone for women with HER2-positive early breast cancer .
Trastuzumab also improves survival for people with HER2-positive metastatic breast cancer (see Table 50).
Learn more about trastuzumab (Herceptin), including possible health risks.
Learn about the strengths and weaknesses of different types of studies.
Study selection criteria: Phase III clinical trials with at least 100 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 when trastuzumab was added to standard treatment.
NS = No statistically significant difference between the 2 treatment groups
*About 2 years of follow-up for each study in the meta-analysis
† All women had hormone receptor-negative tumors 2 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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