By Shira Klapper, Senior Writer/Editor

A new study in the Journal of Clinical Oncology (JCO) confirms that adding trastuzumab to chemotherapy for women with early-stage HER2-positive breast cancer confers sustained and durable benefits in overall survival (OS) and disease-free survival (DFS). The study, published online, ahead of print, October 20, and featured in a JCO Podcast, followed up with women 8.4 years after they had enrolled in a trial from 2000 comparing the chemotherapy regimen of doxorubicin plus cyclophosphamide followed by paclitaxel to the same chemotherapy plus trastuzumab. According to the National Cancer Institute (NCI), OS refers to “the percentage of people in a study or treatment group who are still alive for a certain period of time after they were diagnosed with or started treatment for a disease...” and DFS refers to “... the length of time after primary treatment for a cancer ends that the patient survives without any signs or symptoms of that cancer.”

The study, “Trastuzumab Plus Adjuvant Chemotherapy for HER2-Positive Breast Cancer: Planned Joint Analysis of Overall Survival From NSABP B-31(NRG Oncology) and NCCTG N9831 (Alliance)” is a follow-up to a benchmark study from 2000 that was the first study to show that, after a follow-up of two years, trastuzumab conferred significant survival benefits on women with early stage HER2-positive breast cancer. A second analysis, published in JCO in 2011, followed up with the women after 3.9 years and found a sustained benefit in OS and DFS in women who received trastuzumab.

“We can now conclude for science in general, that adding trastuzumab to chemotherapy for patients with HER2-positive breast cancers significantly improves disease-free progression and overall survival, even in the long term,” said study first author, Edith A. Perez, MD, who co-wrote the 2000 study and the original protocol on which it was based. “This is very reassuring news for everybody to know that the effects we saw in the first studies were not temporary, but are long-lasting.”

Going strong at ten years

Edith A. Perez, MD

The study found that women who received trastuzumab in addition to chemotherapy had an OS that was 37% greater than women who received chemotherapy alone. At 10 years after treatment, 84% of women who received trastuzumab were alive, compared to 75.2% of women who received chemotherapy alone. Additionally, these improvements in OS and DFS were displayed in all subgroups, including older and younger patients, patients with node-positive and node-negative cancers, and patients with ER-positive and ER–negative cancers.

Significant benefits from trastuzumab were also seen in terms of DFS. The DFS among women who received trastuzumab was 40% greater than among women who received chemotherapy alone. At 10 years after treatment, 73.7% of women who received trastuzumab were alive compared to 62.2% of women who did not receive the drug.

The findings also confirmed the long-term safety of trastuzumab; there was no increase in the incidence of secondary cancers and only a minor increase in the possibility of cardiac-related dysfunction.

The benefit of cooperative groups

According to Dr. Perez, the study also shows how the work of cooperative groups—sponsored by NCI— strengthens research. The original study comparing the addition of trastuzumab to chemotherapy alone was based on data gathered from studies sponsored by the North Central Cancer Treatment Group and the National Surgical Adjuvant Breast and Bowel Project.

“This study is an example of how it’s a good strategy to combine efforts of different cooperative groups and patients so that we can identify different ways to tackle the problem of breast cancer,” said Dr. Perez. “I’m very happy that we have been so successful on behalf of our patients.”

Edith A. Perez, MD, is the Deputy Director at large for Mayo Clinic Cancer Center in Jacksonville, Florida, and the Serene M. and Frances C. Durling Professor at Mayo Clinic College of Medicine. She also serves as Chair of the Mayo Clinic Breast Cancer Translational Genomics Program and the Breast Cancer Specialty Council. She has been an ASCO member since 1988 and is a member of the Women with Advanced HER2+ Breast Cancer Committee and the ASCO-CAP HER-2 Testing in Breast Cancer Committee and is past Chair of the Nominating Committee and the Task Force on Health Disparities.

 Source

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Perez EA, RomondEH, Suman VJ. Trastuzumab plus adjuvant chemotherapy for HER2-positive breast cancer: planned joint analysis of overall survival from NSABP B-31(NRG Oncology) and NCCTG N9831 (Alliance). J Clin Oncol. Epub 2014 Oct 20.

The Exclusive Coverage series on ASCO.org highlights selected research from JCO and JOP with additional perspective provided by the lead or corresponding author.

@ 2014 American Society of Clinical Oncology