Women with metastatic breast cancer may have no growth or spread of cancer for longer spans of time if they continue chemotherapy even after the disease is under control, a recent study found. This result supports past research findings that also link longer use of chemotherapy with significantly longer lengths of time before the cancer grows or spreads, as well as somewhat longer overall survival.
While treatments for metastatic breast cancer (MBC) vary based on the hormonal status of the cancer and tumor type, most women with MBC will eventually need chemotherapy. Typically, chemotherapy is given until the cancer cells stop growing or spreading.
Whether continuing chemotherapy after the breast cancer stops growing helps women with MBC live longer without disease progression has been studied before. Yet, the impact of longer treatment on a woman’s quality of life has been inconsistent across previous studies or unaddressed. Many past trials also did not include taxane-based chemotherapy medicines, which are today’s standard of care.
For the current study, investigators compared the effects of extending treatment with a taxane-based chemotherapy combination to stopping treatment once the disease no longer progressed on survival and quality of life. To measure survival benefit, they assessed progression-free survival (PFS), the time from being assigned to a treatment group until the cancer grew or spread, and overall survival (OS), the time from being assigned to a treatment group until death from any cause.
Women with MBC who were not previously treated with chemotherapy for their metastatic disease, were recruited from 10 institutions in Korea between 2007 and 2010. A total of 324 participants enrolled in the study. After six cycles of treatment with the combination of paclitaxel (Taxol) and gemcitabine (PG), the cancer stopped growing in 231 participants.
These 231 women were randomly assigned to two treatment groups: one that continued treatment with PG, and one that stopped treatment until the disease progressed. The two groups were balanced by age, hormonal status, and prior treatment with taxanes. Neither group was allowed treatment with hormonal therapy unless the cancer progressed.
The chemo combination was given to both groups initially, and continued by the PG group, as follows:
- Paclitaxel 175 mg/m² given by vein on day 1, cycle repeated every 21 days
- Gemcitabine 1,250 mg/ m² given by vein on days 1 and 8, cycle repeated every 21 days
All participants had blood tests every treatment cycle, imaging every 6 weeks, and were assessed for side effects on the first day of each cycle. The chemotherapy dose was lowered if a woman had severe side effects.
Overall, researchers found that women who continued treatment with PG experienced much longer PFS and somewhat longer OS than women who stopped treatment entirely once the disease was stable. In addition, they found that there were no differences in quality of life between the two groups.
The data showed
- the median PFS time was 3.7 months longer in the PG group
- the 6-month PFS rate was 66 percent higher in the PG group (59.7% in the PG maintenance arm and 36.0% in the observation arm)
- the median OS was slightly longer in the maintenance group compared with the observation group (32.3 months vs. 23.5 months)
- the women most likely to benefit from continuing treatment with PG were younger than age 50, still had their monthly period, had hormone receptor-negative disease, had two or more metastases, or had metastases to organs rather than to bone
What This Means for You
The findings reported in this study support past results that suggest women with MBC who continue chemotherapy after the cancer stops growing may live for longer periods of time before the disease grows again.
How long a woman with metastatic breast cancer continues treatment with chemotherapy will vary depending on health-specific factors unique to her. It is important to note that the women enrolled in this trial were in reasonably good physical health and had acceptable liver and kidney function.
If you are a woman with metastatic breast cancer, how a treatment impacts your quality of life may be as or more important to you than how effective the treatment is. It may comfort you to know that extended treatment with PG may improve PFS without having a negative effect on your day-to-day life.
Your healthcare team will work with you to determine what treatments are best for you. Talk with them about these and similar findings. Remember that it is OK to let them know if you have concerns about how a medicine may impact your quality of life.
Park, Y. H., Jung, K.H., Im, S., et al. Phase III, multicenter, randomized trial of maintenance chemotherapy versus observation in patients with metastatic breast cancer after achieving disease control with six cycles of gemcitabine plus paclitaxel as first-line chemotherapy: KCSG-BR07-02. Journal of Clinical Oncology. 2013; 31 (14): 1732-1740.