Trastuzumab-Paclitaxel Combo Very Effective for Small HER2-Positive Breast Cancers
A study looked at people with stage I and small stage II HER2-positive breast cancer that hadn't spread to the lymph nodes. It found that treatment with trastuzumab and the chemotherapy medicine paclitaxel kept the vast majority of participants alive and free from breast cancer recurrence 3 years after taking it. This treatment also caused few serious side effects.
Background and Goals
HER2-positive breast cancer has too many human epidermal growth factor receptor 2 proteins on cells. Treatment for this type of breast cancer usually includes adjuvant, or post-surgery, therapy with chemotherapy and trastuzumab (Herceptin). Trastuzumab is an anti-cancer medicine that targets HER2 and lowers the risk of recurrence, or cancer returning, by 50 percent compared with chemotherapy alone.
Stages are assigned to breast cancer based on tumor size, lymph node involvement and whether the breast cancer has spread to other parts of the body. Stage I means the tumor is 2 centimeters or smaller and has not spread outside the breast. Relatively few people with small tumors that haven’t spread to the lymph nodes have previously been included in clinical trials, but it’s thought that without adjuvant treatment these people would have a 5 to 30 percent risk of recurrence.
The usual adjuvant therapies for HER2-positive breast cancer include multiple chemotherapy medicines plus trastuzumab. These regimens can cause serious side effects. People may not want to take the chance of getting those side effects if their risk of recurrence is already low.
These researchers looked at how small, HER2-positive breast cancers that haven’t spread to the lymph nodes respond to a simpler regimen of trastuzumab and one chemotherapy medicine, paclitaxel (Taxol). They also looked at this treatment’s side effects.
To be eligible for this study, participants had to have breast cancer tumors no bigger than 3 centimeters and no cancer in their lymph nodes. They also had to be in good general health.
The following treatment was assigned to 406 participants:
- weekly paclitaxel, by vein, for 12 weeks.
- weekly trastuzumab, by vein, for 12 weeks. After that, trastuzumab was given weekly or every 3 weeks for 40 more weeks, to equal one year of trastuzumab.
The researchers focused on invasive disease-free survival, IDFS, the time from the start of study treatment to the breast cancer coming back in the same breast or nearby lymph nodes, breast cancer spreading to other parts of the body, new breast cancer, or death from any cause.
After 3 years of follow-up, almost all the participants were alive and free of invasive disease – the IDFS rate was 98.7 percent.
Side effects are grouped according to how serious they are. Grade 2 is moderate; grade 3 is severe; grade 4 is life threatening or disabling. The most common grade 2-4 side effects were:
- Fatigue (22.2 percent of participants)
- Diarrhea (13.1 percent of participants)
- Neuropathy - pain, numbness, tingling, or muscle weakness in different parts of the body (13.1 percent of participants)
- Neutropenia, or low white blood cell count, which can make infections more likely (10.6 percent of participants)
- High blood sugar (10.3 percent of participants)
- Allergic reaction (8.6 percent of participants)
- Liver inflammation (7.4 percent of participants)
- Anemia - low red blood cell count (7.1 percent of participants)
Less than 1 percent of these side effects were grade 4 and more than 80 percent of them were grade 2.
Heart problems are a rare but serious side effect of trastuzumab. In this study, two people got congestive heart failure, in which the heart doesn't pump blood as well as it should – but their hearts returned to normal after stopping trastuzumab. Thirteen people had to stop taking trastuzumab because of poor readings on tests that measure heart health, but 11 were able to start taking it again after a short break.
Randomized controlled trials are the gold standard of treatment. They involve comparing a new treatment to a standard treatment and comparing the results. However, there was no comparison group in this study.
What This Means for You
Ninety percent of the participants in the trial had stage I breast cancer, so the results apply mostly to people at that stage. If you have stage I HER2-positive breast cancer, your treatment path isn't as clear as the path of someone with higher-stage disease. The National Comprehensive Cancer Network (NCCN) says trastuzumab and chemotherapy should be a treatment option for you. But they also note that little research has been done in people like you.
People with larger HER2-positive breast cancers are often treated with an AC-TH regimen, made up of the chemotherapy medicines doxorubicin (Adriamycin), cyclophosphamide (Cytoxan) and paclitaxel, along with trastuzumab. But using two of those medicines, instead of all four, kept most participants alive and breast cancer-free without exposing them to extra side effects. These researchers say their results are encouraging, but aren't strong enough to recommend that all people with small HER2-positive breast cancers that haven't spread to the lymph nodes receive the study treatment.
Talk to your doctor about your risk of cancer returning and your treatment plan. Your lifestyle, financial situation, feelings about recurrence and willingness to deal with side effects could all affect what you decide to do. Some people choose to have adjuvant treatment for stage I HER2-positive breast cancer. Others don’t. Neither decision is wrong. But it’s important to know the pros and cons of your options.
To learn more, read our Guide to Understanding Treatment Decisions.
Tolaney, Sara M.; Barry, William T.; Dang, Chau T. Adjuvant Paclitaxel and Trastuzumab for Node-Negative HER2-Positive Breast Cancer. The New England Journal of Medicine. January 8, 2015; doi: 10.1056/NEJMoa1406281.