10 Years of Arimidex Reduces Recurrence Risk, But Doesn’t Improve Overall Survival
Taking the hormonal therapy Arimidex (chemical name: anastrozole) for 10 years after surgery to remove hormone receptor-positive breast cancer reduced the risk of the cancer coming back (recurrence), but didn’t improve overall survival, according to a Japanese study.
The research was published online on April 20, 2023, by the Journal of Clinical Oncology. Read the abstract of “Postoperative Adjuvant Anastrozole for 10 or 5 Years in Patients With Hormone Receptor-Positive Breast Cancer: AERAS, a Randomized Multicenter Open-Label Phase III Trial.”
Doctors call treatment given after surgery adjuvant treatments.
Overall survival is how long a person lives, with or without the cancer coming back.
About Arimidex
Arimidex is a type of hormonal therapy called an aromatase inhibitor.
Arimidex is used:
to reduce the risk of hormone receptor-positive, early-stage breast cancer coming back in post-menopausal women after surgery
as a first treatment for hormone receptor-positive, advanced-stage breast cancer in post-menopausal women
to treat advanced-stage breast cancer that has grown after tamoxifen treatment in post-menopausal women
Hormonal therapy after breast cancer surgery
For many years, women have taken hormonal therapy for five years after surgery for early-stage, hormone receptor-positive breast cancer. In many cases, the standard of care is five years of tamoxifen, or two to three years of tamoxifen followed by two to three years of an aromatase inhibitor, depending on menopausal status.
More recent research has found that in certain cases, taking tamoxifen for 10 years instead of five years after surgery lowered a woman’s risk of recurrence and improved survival.
Sometimes breast cancer is found in the lymph nodes (called node-positive disease) of post-menopausal women diagnosed with early-stage, hormone receptor-positive breast cancer. In this case, doctors would recommend an aromatase inhibitor for an additional five years, for a total of 10 years of hormonal therapy treatment.
Doctors call taking hormonal therapy for 10 years after surgery extended adjuvant hormonal therapy.
About the study
The American Society of Clinical Oncology (ASCO) updated its guidelines on adjuvant hormonal therapy in 2018, recommending post-menopausal women diagnosed with early-stage, node-positive, hormone receptor-positive breast cancer take hormonal therapy, including an aromatase inhibitor, for 10 years after surgery.
Still, broader research on the benefits of taking an aromatase inhibitor for 10 years after surgery has offered mixed results. Some of the studies looking at taking five years of an aromatase inhibitor after five years of tamoxifen showed benefits. Other studies looking at taking an additional five years of an aromatase inhibitor after the first five years of an aromatase inhibitor showed little benefit.
In this study, the researchers wanted to add more information to the topic.
The study included 1,593 women diagnosed with early-stage, hormone receptor-positive breast cancer that was removed with surgery.
Most of the women were diagnosed with stage I or stage IIA, node-negative disease and had lumpectomy followed by radiation. About 39% of the women also received chemotherapy.
All the women took hormonal therapy for five years after surgery:
144 women took tamoxifen for the first one to three years after surgery; after they completed tamoxifen, they took Arimidex, completing a total of five years of hormonal therapy
1,449 women took Arimidex for five years after surgery
The researchers randomly assigned the women to one of two groups:
806 women were in the stop group; they stopped taking hormonal therapy after five years
787 women were in the continue group; they took an additional five years of Arimidex for a total of 10 years of hormonal therapy
The researchers looked at disease-free survival rates in both groups. The disease-free survival rate is the percentage of women who were alive without the cancer coming back.
Five-year disease-free survival rates were:
91% for women in the continue group (took five more years of Arimidex)
86% for women in the stop group (stopped hormonal therapy after five years)
This difference was statistically significant, which means it was likely because of the difference in treatment and not just due to chance.
The researchers also looked at how many women died in each group:
21 women in the continue group died
19 women in the stop group died
Essentially, there was no difference in overall survival.
The researchers reported that side effects such as hot flashes and joint pain happened more often in women in the continue group. Rates of specific side effects were as follows:
10% of women in the stop group and 14% of women in the continue group had hot flashes
44% of women in the stop group and 47% of women in the continue group had osteoporosis
9% of women in the stop group and 10% of women in the continue group broke a bone
12% of women in the stop group and 21% of women in the continue group had joint stiffness
Still, fewer than 1% of women in each group had a side effect that was grade 3 or worse.
“Continuing adjuvant anastrozole for an additional five years after five years of initial treatment with anastrozole or tamoxifen followed by anastrozole was well tolerated and improved [disease-free survival],” the researchers concluded. “Although no difference in overall survival was observed as in other trials, extended anastrozole therapy could be one treatment choice in post-menopausal patients with hormone receptor-positive breast cancer.”
What this means for you
If you’ve been diagnosed with early-stage, hormone receptor-positive breast cancer and are finishing up five years of Arimidex, you may want to ask your doctor about this study and whether taking Arimidex for another five years — for a total of 10 years of Arimidex — makes sense for you and your unique situation. Talk to your doctor about any side effects you’ve been having and whether the benefits of another five years of Arimidex outweigh the risks of side effects.
Together, you can decide on a treatment plan that’s best for you.
Learn more about hormonal therapy.
— Last updated on June 20, 2023 at 3:08 PM