|Two Types of Breast Cancer Treatments Show Similar Benefit
Results from a clinical trial comparing the effectiveness of the drugs paclitaxel
and docetaxel, delivered over two different dosing schedules, showed that both
drugs — regardless of the dosing schedules tested in this trial — provided
similar benefits for women with stage II or III, operable breast cancer. However,
more women treated with docetaxel than with paclitaxel experienced serious side
effects from their treatment. The trial was led by the Eastern Cooperative Oncology
Group in collaboration with the Cancer and Leukemia Group B, North Central Cancer
Treatment Group (NCCTG), and the Southwest Oncology Group*. The National Cancer
Institute (NCI), part of the National Institutes of Health, supported this Phase
III randomized clinical trial. The results were presented at the San Antonio
Breast Cancer Symposium on December 8, 2005**.
Paclitaxel and docetaxel are members of a class of drugs called taxanes, and
both are approved for the treatment of patients with breast cancer that has spread
to the lymph nodes. Although these drugs have been shown to be beneficial in
treating breast cancer, this is the first time they have been directly compared
and the first time that a weekly dosing schedule has been compared with a standard
every three-week dosing schedule in the treatment of early-stage breast cancer.
“Although both drugs are used as adjuvant breast cancer treatments, which taxane
and which schedule are most effective has been a question for many years,” said
JoAnne Zujewski, M.D., who oversees breast cancer trials for NCI's Cancer Therapy
Evaluation Program. “Now doctors and patients will be able to consider side effects,
convenience, and cost in determining taxane treatment without concern that effectiveness
will be compromised.”
A total of 4,988 women were enrolled in the trial between 1999 and 2002. All
of the women had axillary lymph node (a lymph node in the armpit region that
drains lymph channels from the breast) positive or high-risk (their tumor was
at least 2 centimeters in size) node-negative breast cancer. All of the women
were first treated with doxorubicin and cyclophosphamide, a standard treatment
protocol referred to as AC (representing the drugs doxorubicin and cyclophosphamide).
Following AC chemotherapy, patients were randomly assigned to groups that received
either paclitaxel or docetaxel, administered weekly for 12 weeks or every third
week over a 12-week period.
The women were followed for a median time of about four years. Over the course
of this period, the investigators observed 856 disease-free survival events across
all regimens. Disease-free survival is the time during which no cancer is found.
In contrast, disease-free survival events have a different meaning. They are
defined as a recurrence of breast cancer, a new second primary breast cancer
in the opposite breast, or death without evidence of recurrent breast cancer.
The vast majority of women (83 percent) remain event-free at this time.
This trial also compared the efficacy of different taxane treatment schedules,
using paclitaxel given every three weeks as the current standard of care. In
this secondary analysis, there was a trend toward fewer disease-survival events
among women who received weekly paclitaxel treatments compared with paclitaxel
given every three weeks.
"Previous studies in patients where cancer had spread to other parts of the
body have shown that docetaxel is more effective than paclitaxel when given every
3 weeks, and that paclitaxel is more effective if given weekly rather than every
3 weeks, " said Joseph Sparano, M.D., professor of medicine at the Albert Einstein
College of Medicine in New York City, and director of the Breast Evaluation Center
at the Montefiore-Einstein Cancer Center, and clinical trial leader. "This study
addressed a question that many medical oncologists have had for some time about
whether this would translate into improved success rates for patients with stage
II and III disease. At this time, this does not appear to be the case, but further
follow-up will be required to confirm our initial findings.”
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