Aromatase Inhibitor Adverse Effects Are Like "Menopause Plus"

Study focuses on "new onset" of symptoms

Nick Mulcahy

November 11, 2010

November 11, 2010 (Philadelphia, Pennsylvania) — Aromatase inhibitors (AIs) are associated with the new onset of a wide array of symptoms, such as hot flashes and leg cramps, according to a new study.

The study is "one of the first" to look at the effects of AIs in a clinic setting rather than a randomized clinical trial, said the lead author, Lisa Gallicchio, PhD, from the Prevention and Research Center at Mercy Medical Center in Baltimore, Maryland.

Randomized controlled trials of AIs have firmly established that musculoskeletal symptoms are related to treatment, said Dr. Gallicchio. But what about other symptoms that many women on AIs seem to experience?

To examine the problem, the investigators performed a clinical study and compared a group of women receiving AIs to a control group that "is not a tamoxifen-taking group," which was the case in the randomized trials.

The control group in the study was "without cancer and not on cancer medication," said Dr. Gallicchio.

"The healthy controls help us understand which symptoms of the women on AIs are drug related," she explained.

Dr. Gallicchio spoke at a press conference here at the Ninth Annual American Association for Cancer Research (AACR) International Conference on Frontiers in Cancer Prevention Research, where she presented the study results.

The symptoms that are apparently associated with AIs are legion.

The investigators compared 100 postmenopausal women who had breast cancer and were taking AIs with 200 age-matched women without cancer at baseline, 3 months, and 6 months. The average age of the participants was around 61 years. They found that women taking AIs, in terms of new onset of symptoms during the study period, were:

  • 5 times more likely to report having hot flashes, breast sensitivity, and chest pain than healthy women

  • 4 times more likely to report night sweats, cold sweats, and hair loss

  • about 3 times more likely to report leg cramps, weight gain, sleep disturbance, tendency to take naps, and forgetfulness.

The difference in frequency between the 2 groups in the new onset of all of these symptoms was statistically significant, said Dr. Gallicchio. Furthermore, when the women taking AIs were divided into those who received chemotherapy and those who did not, the statistical significance remained in all cases, except forgetfulness.

Other increased symptoms that were not statistically significant included intestinal gas, cough, depression, interrupted sleep, and irritability.

"This is like menopause plus," said Judy Garber, MD, MPH, director of the Center for Cancer Genetics and Prevention at the Dana-Farber Cancer Institute, Boston, Massachusetts, and president-elect of the AACR. Dr. Garber moderated the press conference.

She pointed out that the symptoms "tend to run together" — hot flashes lead to sleep disturbance, which leads to forgetfulness, and so on.

Clinicians should ask about these symptoms, said Dr. Garber. Dr. Gallicchio advised clinicians to "switch AIs to see if that helps with the side-effect profile."

Dr. Gallicchio reported that the symptoms not associated with AI treatment in the study were constipation, vaginal discharge, vaginal bleeding, vaginal dryness, painful intercourse, dry mouth, weight loss, decreased appetite, fatigue, incontinence, fever, nausea, upset stomach, headache, and vomiting.

Study Details in Context

Dr. Gallicchio said that research into the adverse effects of AIs is "about to explode," meaning that researchers have now turned their attention to this troubling aspect of the highly effective treatments.

Dr. Garber said that her colleague at Dana-Farber, Anne Partridge, MD, has done some of the groundbreaking research in the area. She also said that AIs have seemed so "attractive" because, unlike tamoxifen, which is an alternative chemoprevention, they did not cause uterine cancer. "But the truth is, these drugs do cause a lot of side effects," said Dr. Garber. "It appears to be a much worse profile" than originally thought, she added.

"These symptoms may [affect] quality of life and ultimately medication adherence," said Dr. Gallicchio. Medication adherence is crucial in reducing the risk for recurrence and breast-cancer-related mortality, she reminded the audience.

AIs are typically prescribed for 5 years and result in an "extreme estrogen-deficient state," said Dr. Gallicchio.

In a recently published study from the large Kaiser Permanente HMO, only about half of women taking AIs took their pills for the full course, she said.

The matters of adherence and adverse effects will be in the spotlight further, because 2 trials, one in Canada and the other in Europe, are employing AIs for the prevention of breast cancer in women without the disease, said Dr. Garber.

The study was funded by Susan G. Komen for the Cure, AstraZeneca, and the National Cancer Institute. The researchers have disclosed no relevant financial relationships.

Ninth Annual American Association for Cancer Research (AACR) International Conference on Frontiers in Cancer Prevention Research: Abstract B10. Presented November 11, 2010.

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