Many women diagnosed with early-stage breast cancer with a high risk of recurrence (the cancer coming back) get chemotherapy after surgery to reduce the risk of recurrence. In some cases, the chemotherapy may be given on a dose-dense schedule.
Dose-dense chemotherapy means that the chemotherapy medicines are given every 2 weeks instead of the standard schedule of every 3 weeks. Doctors may recommend a dose-dense regimen for some women because other research has shown that this approach can improve survival and decrease the risk of recurrence more effectively than a standard chemotherapy schedule.
Dose-dense chemotherapy regimens are used more often in the United States than they are in Europe.
A study has found that premenopausal women diagnosed with early-stage breast cancer with a high risk of recurrence have better survival if they are treated with a dose-dense chemotherapy regimen. The study also found that the dose-dense regimen doesn’t seem to increase the risk of treatment-related early menopause (also called treatment-induced amenorrhea by doctors).
The study was presented on March 10, 2016 at the 2016 European Breast Cancer Conference. Read the abstract of “Dose-dense adjuvant chemotherapy, treatment-induced amenorrhea and overall survival in premenopausal breast cancer patients: A pooled analysis of the MIG1 and GIM2 phase III studies.”
To do this study, the researchers analyzed the results of two trials looking at a dose-dense chemotherapy regimen versus a standard chemotherapy regimen after surgery:
- In the MIG1 study, women diagnosed with early-stage breast cancer with a high risk of recurrence were randomly assigned to receive six cycles of the fluorouracil-Ellence (chemical name: epirubicin)-Cytoxan (chemical name: cyclophosphamide) combination either every 2 weeks (dose-dense) or every 3 weeks (standard). This chemotherapy combination is commonly called FEC. In this study, the researchers said treatment-related early menopause meant that a woman wasn’t having periods 3-6 months after chemotherapy ended.
- In the GIM2 study, women diagnosed with early-stage breast cancer with a high risk of recurrence were randomly assigned to receive four cycles of FEC or EC (Ellence and Cytoxan) on either a dose-dense or standard regimen. This was followed by four cycles of Taxol (chemical name: paclitaxel) on either a dose-dense or standard regimen. In this study, the researchers said treatment-related early menopause meant that a woman wasn’t having periods 1 year after chemotherapy ended.
Together, the two studies included 3,305 women. A total of 1,549 women were premenopausal and were included in this analysis:
- 528 from the MIG1 study
- 1,021 from the GIM2 study
Half of these women were older than 44 and half were younger.
The researchers found that dose-dense chemotherapy led to better 10-year overall survival rates:
- 84.9% of the women on the dose-dense regimen in the MIG1 study were alive after 10 years
- 79.1% of the women on the standard regimen in the MIG1 study were alive after 10 years
- 88.0% of the women on the dose-dense regimen in the GIM2 study were alive after 10 years
- 77.3% of the women on the standard regimen in the GIM2 study were alive after 10 years
These differences were statistically significant, which means that they were likely due to the difference in regimens and not just because of chance.
Overall survival is how long a woman lives, with or without the cancer coming back.
The survival benefits of dose-dense chemotherapy didn’t seem to depend on the hormone-receptor status of the cancer, though women diagnosed with hormone-receptor-negative disease had slightly better 10-year survival than women diagnosed with hormone-receptor-positive disease. Still, this difference wasn’t statistically significant, which means that it could have been due to chance.
Dose-dense chemotherapy also didn’t seem to increase the risk of treatment-related early menopause. Treatment-related early menopause didn’t seem to be related to overall survival.
“The take-home message of our study is that dose-dense adjuvant chemotherapy is associated with a significant improvement in overall survival as compared to standard-interval chemotherapy in high-risk, premenopausal breast cancer patients,” said Matteo Lambertini, M.D., medical oncologist at the National Institute for Cancer Research in Genoa, Italy, when he presented the research.
It’s important to know that this study didn’t look at any differences in side effects, such as hand-foot syndrome or low white blood cell counts, between the dose-dense and standard regimen groups. Other studies have found that dose-dense chemotherapy regimens may cause more side effects than standard regimens.
It’s also important to know that Ellence is more commonly used in Europe, so this study may not reflect standards of care in the United States. A typical U.S. dose-dense chemotherapy regimen is more likely to involved Adriamycin (chemical name: doxorubicin) and Cytoxan followed by Taxol.
If you’re a premenopausal woman who’s been diagnosed with breast cancer that has a high risk of recurrence, it’s likely that chemotherapy will be part of your treatment plan. This and other studies suggest that a dose-dense chemotherapy regimen may offer more benefits than a standard regimen. After you consider all the characteristics of the cancer, as well as your unique situation and preferences, you and your doctor can make the best choices for you.
Visit the Breastcancer.org Chemotherapy section to learn more about what to expect during chemotherapy.