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Published on December 15, 2020
Research Says Women with Postmenopausal Breast Cancer May Be Able to Forego Chemotherapy
Postmenopausal women with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer may be able to forgo chemotherapy, according to the results of a study presented at the San Antonio Breast Cancer Symposium (SABCS).
The study found that if the cancer is limited to a small number of lymph nodes, and the risk of recurrence is relatively low, postmenopausal women do not benefit from chemotherapy when the treatment is added to hormone therapy.
The findings are the first evidence that postmenopausal women can avoid chemotherapy and spare themselves “the time, money, and harmful side effects that come with chemotherapy infusions,” stated a press release announcing the results.
“Every day in clinics around the world, physicians wrestle with the question of how to best treat women with this common form of breast cancer,” said the lead author of the study, Dr. Kevin Kalinsky, director of the Glenn Family Breast Center at the Winship Cancer Institute of Emory University in Atlanta. “These results are practice-changing and demonstrate that postmenopausal women can be spared unnecessary chemotherapy and receive only hormone therapy. This should bring more clarity to physicians and some relief for patients.”
The study, SWOG S1007, known as RxPONDER, was conducted by the Portland, Oregon-based SWOG Cancer Research Network at 632 sites in nine countries: the United States, Canada, Mexico, Colombia, Ireland, France, Spain, South Korea and Saudi Arabia. SWOG is a part of the National Cancer Institute’s (NCI) National Clinical Trials Network and the NCI Community Oncology Research Program.
RxPONDER looked at 5,083 women who had HR-positive, HER2-negative breast cancer that had spread to one to three lymph nodes, with recurrence scores of 25 or less. The women were randomly assigned to receive hormone therapy alone or hormone therapy plus several months of intravenous chemotherapy. Two-thirds of the women in the trial were postmenopausal, and data from 5,015 eligible patients was used to conduct the analysis.
Researchers found postmenopausal patients with a higher recurrence score did not benefit more from chemotherapy than those with a lower score. Among the group, the five-year invasive disease-free survival (IDFS) rate was 91.6% for the chemotherapy plus hormone therapy group and 91.9% for the hormone therapy-only group.
What About Pre-Menopausal Women?
Among premenopausal women, there was a significant benefit from chemotherapy, the study found. The five-year IDFS rate in premenopausal women was 94.2% for the chemotherapy and hormone therapy group, compared with 89.0% for the hormone therapy-only group.
It is unclear why premenopausal women benefited from chemotherapy while postmenopausal women did not. The release states that one possible explanation is that chemotherapy can induce menopause, starving the cancer of the hormones it needs to grow.
Additional research is needed to explore whether a treatment that induces menopause given in combination with standard hormone therapy would have the same effect on the risk of recurrence as that seen in this study.
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