After breast cancer surgery, women diagnosed with early-stage, HER2-positive breast cancer usually receive the targeted therapy medicine Herceptin (chemical name: trastuzumab) and a combination of chemotherapy medicines. Treatments given after surgery are called adjuvant therapies and are used to lower the risk of the cancer coming back (recurrence).
In the United States, Herceptin is approved to be given at two times:
- at the same time as chemotherapy (concurrently)
- after chemotherapy is done (sequentially)
Still, Herceptin usually is given concurrently in the United States. In other countries, Herceptin is approved only to be given sequentially.
A study found that women who got Herceptin at the same time as chemotherapy were 25% less likely to have a breast cancer recurrence than women who got Herceptin after chemotherapy. These results were presented at the 2009 San Antonio Breast Cancer Symposium.
In this study, 3,133 women diagnosed with HER2-positive, early-stage breast cancer got the chemotherapy combination of:
- Adriamycin (chemical name: doxorubicin)
- Cytoxan (chemical name: cyclophosphamide)
- Taxotere (chemical name: docetaxel)
The women randomly were split into three groups:
- one group got Herceptin that started at the same time as Taxotere
- the second group got Herceptin that started after chemotherapy was completed
- the third group got only chemotherapy (no Herceptin)
The women who got Herceptin received it for a total of 52 weeks.
To see if the timing of Herceptin treatment made a difference, the researchers looked the risk of recurrence 5 years after treatment.
- 84.2% of the women who got Herceptin at the same time as chemotherapy were alive with no recurrence (disease-free survival)
- 80.1% of women who got Herceptin after chemotherapy were alive with no recurrence
This difference was statistically significant, which means that it was likely due to the timing of Herceptin treatment and not because of chance. While this difference in disease-free survival may seem small, it is a 25% lower risk of recurrence for women who got Herceptin at the same time as chemotherapy instead of after.
Other research has shown that women diagnosed with HER2-positive, early-stage breast cancer treated with Herceptin have a lower risk of recurrence than women not treated with Herceptin. So in this study, women in the chemotherapy-only group (no Herceptin) could start taking Herceptin if they wanted to do so. When a group in a study switches to a different treatment, researchers call it a crossover. Also, when preliminary results form this study suggested that getting Herceptin at the same time as chemotherapy was better than getting Herceptin after chemotherapy, women were allowed to switch to concurrent Herceptin (another crossover).
Crossover can make the analysis of a study more complicated, so researchers sometimes do a separate analysis that excludes all crossover results. When the researchers did a separate analysis with no crossover results for this study, they found an even greater reduction in the risk of recurrence for Herceptin given at the same time as chemotherapy: recurrence was 33% less likely with Herceptin given at the same time as chemotherapy compared to Herceptin given after chemotherapy.
Both Herceptin and Adriamycin can cause heart problems, including decreased heart function and heart failure. In this study, 3.3% of women who got Herceptin and chemotherapy at the same time developed heart problems compared to 2.8% of the women who got Herceptin after chemotherapy. Only 0.3% of the women who received chemotherapy and no Herceptin developed heart problems.
Based on the results, most doctors think that giving Herceptin at the same time as chemotherapy rather than after chemotherapy should be the standard when treating women diagnosed with early-stage, HER2-positive breast cancer.
If you've been diagnosed with HER2-positive, early-stage breast cancer, your doctor will likely recommend Herceptin and chemotherapy after surgery to reduce the risk of the cancer coming back. Your doctor probably will plan on starting Herceptin during chemotherapy. Still, if your doctor recommends starting Herceptin treatment after chemotherapy is completed, you might want to ask why and talk about the results of this study. Armed with the most-up-to-date information, you and your doctor can decide on a treatment plan that makes the most sense for your and your unique situation.