The small study reviewed here found that post-menopausal women diagnosed with hormone-receptor-positive, early-stage breast cancer who took the aromatase inhibitor Arimidex (chemical name: anastrozole) were no more likely than women who got a placebo to have memory or thinking problems in the 2 years after starting Arimidex.
About half of the 207 women in the study took Arimidex after surgery to remove the breast cancer. The other half of the women received a placebo (a "dummy" or sugar pill) after surgery. Many of the women in the study also received radiation therapy and chemotherapy after surgery.
All of the women had cognitive testing -- tests that measure memory and thinking skills -- three times during the study:
During the 6-month and 2-year cognitive tests, the women also reported whether they felt their ability to remember and concentrate had declined.
Before starting Arimidex or the placebo, about a quarter of the women -- 20 women scheduled to take Arimidex and 24 women scheduled to take the placebo pill -- had cognitive test scores that suggested some problems with memory and thinking. These thinking and memory problems couldn't have been caused by Arimidex because the treatment hadn't started yet. A number of other factors related to breast cancer may have caused the thinking and problems, including the physical and emotional stress of being diagnosed and treated, anesthesia used during surgery, or chemotherapy.
Six months after treatment started, a few more women had cognitive test scores that indicated thinking and memory problems:
This slight increase was basically the same whether the women were taking Arimidex or the placebo. So the 6-month results suggested that Arimidex didn't cause thinking and memory problems.
The cognitive tests done 2 years after treatment started showed that fewer women had cognitive test scores that indicated thinking and memory problems compared to the first baseline test:
The number of women with abnormal cognitive test results were very similar whether the women were taking Arimidex or the placebo pill. So the 2-year results also suggested that Arimidex doesn't cause thinking and memory problem.
The researchers analyzed the self-reported memory and concentration problems and there weren't any real differences between the women who got Arimidex compared to the women who got the placebo pill. A small number of women in both groups reported problems, but the problems tended to get better over time.
At 6 months:
At 2 years:
While this study didn't show that Arimidex caused any thinking and memory problems, this was a small study and the women were only followed for 2 years. Some of the women in the study also got chemotherapy, which IS associated with thinking and memory problems (known as chemobrain or chemofog). Also, this study only looked at one aromatase inhibitor, Arimidex. It's not clear if these results would apply to the two other aromatase inhibitors: Aromasin (chemical name: exemestane) and Femara (chemical name: letrozole).
Hormonal therapy medicines are used after initial breast cancer treatment to lower the risk of the breast cancer coming back and are usually given for 5 years. While this study suggests that Arimidex doesn't cause memory and thinking problems, aromatase inhibitors and tamoxifen, another hormonal therapy, can cause bothersome side effects. Tamoxifen (which works differently than aromatase inhibitors) can cause hot flashes. Aromatase inhibitors also can cause hot flashes as well as muscle and joint pain. In this research, 30% of the women who took Arimidex reported hot flashes, compared to only 15% of the women who took the placebo pill.
If you're worried about the side effects of hormonal therapy or are currently having troubling side effects, talk to your doctor about how best to manage them. You may be able to take a different hormonal therapy medicine. If you're taking hormonal therapy medicine now, stick with it as prescribed. If you're thinking of stopping early or not starting a treatment because you're afraid of side effects, talk to your doctor first. Together, you can find a solution that is best for YOU.
For more information, visit the Breastcancer.org Staying on Track with Hormonal Therapy page. You can read about why it's so important to stick to your treatment plan, as well as ways to manage side effects.
BRIGHTON, England, Sept. 3 (MedPage Today) -- In postmenopausal women at high risk for breast cancer, two years of prophylaxis with an aromatase inhibitor did not lead to cognitive impairment, according a placebo-controlled study.
Scores on tests of cognitive function did not differ at any time point between patients treated for 24 months with anastrozole (Arimidex) or placebo, Valerie A. Jenkins, D.Phil., of the University of Sussex, and colleagues reported online in Lancet Oncology.
Similar numbers of patients in each group reported changes in memory after six months, and the number of affected patients decreased to a handful by the end of the study.
"The current study does not provide clear evidence that anastrozole, compared with placebo, produced cognitive impairments over a 24-month period," the authors said.
"These findings should be reassuring in the short term for postmenopausal women being treated with anastrozole, their clinicians, and carers," they added.
Some evidence has suggested an adverse effect of endocrine therapy on cognitive function in breast cancer patients. However, the few trials designed to examine the issue have been confounded by previous use of chemotherapy, small sample size, and various methodologic issues, the authors noted.
The International Breast Intervention Study (IBIS) II provided an opportunity to conduct a prospective evaluation of endocrine therapy's effects on cognitive performance.
IBIS II involves postmenopausal women at high risk for breast cancer because of family history, prior benign breast disease with evidence of proliferation or atypia, or nulliparity plus first-degree family history. The patients have been randomized to five years of preventive therapy with anastrozole or to placebo.
Dr. Jenkins and colleagues conducted a cognitive function substudy of 207 IBIS II participants. The patients completed a set of standardized cognitive tasks at baseline, six months, and 24 months. Psychological morbidity, endocrine symptoms, and self-reported cognitive complaints also were assessed.
The primary endpoint was change in cognitive task scores over 24 months of follow-up. By the end of the study, 56 patients had been excluded from the two treatment arms, leaving 151 for analysis.
At baseline 24 placebo patients and 20 anastrozole patients had cognitive task scores indicative of some impairment. At six months, the number of patients with suggestive scores was 27 in the placebo group and 24 in the anastrozole group, declining to 23 and 17, respectively, by 24 months.
After six months 13 patients in each group had self-reported memory changes, declining to five in the placebo group and three in the anastrozole group between six and 24 months. Similarly, the number of patients with self-reported changes in concentration at six months was 11 with placebo and seven with anastrozole, decreasing to two in each group by 24 months.
The only significant difference between treatment groups was the frequency of hot flushes, reported by 30% of anastrozole patients and 15% of placebo patients (P=0.032).
The authors, emphasizing the fact that the study was only for 24 months, pointed out that the longer-term effects, alone or after chemotherapy treatment, are unknown.
They also noted that "at present, cognitive research in this area is restricted by methodological challenges and the absence of standardization in neuropsychological studies. An international task force has been proposed to provide guidelines for future research to address these issues."
The study was supported by Cancer Research U.K.
Co-author Jack Cuzick, Ph.D., reported that he has served as a consultant for AstraZeneca. None of the other authors reported potential conflicts of interest.
Primary source: Lancet Oncology Source reference: Jenkins VA, et al "Effects of anastrozole on cognitive performance in postmenopausal women: a randomized, double-blind chemoprevention trial (IBIS II)" Lancet Oncol 2008; DOI: 10.1016/S1470-2045(08)70207-9.
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