FRIDAY, Sept. 2, 2005 (HealthDay News) -- An increasingly popular group of breast cancer drugs apparently has a downside that few are familiar with.
A review article in the September issue of Arthritis & Rheumatism attempts to heighten awareness about the effect of aromatase inhibitors on joint pain.
"The reason for the concern now is that they're becoming more popular, and I think they're going to be very widely used, and this is something we need to be concerned about," said Dr. David T. Felson, principal author of the article and a professor of medicine at Boston University School of Medicine. "The medical community doesn't even know this exists. We're going to be seeing these women, and need to be familiar with this, otherwise women will suffer without knowing why."
Aromatase inhibitors are hormonal treatments for estrogen receptor-positive breast cancer. The drugs work by reducing estrogen levels in the body's tissue, and are already widely used to reduce recurrence rates in women with early-stage postmenopausal breast cancer. Experts feel they may also have a role to play in preventing breast cancer in women who are at high risk.
They are part of a larger group of estrogen-deprivation therapies that include tamoxifen. "It's only with estrogen deprivation that this occurs," Felson said of the joint pain.
Many also worry that the drugs are being overused, and that side effects are being downplayed.
"My impression is that the oncology community has jumped on this category of drugs in lieu of tamoxifen in a huge number of people much too quickly," said Dr. Steven Goldstein, a professor of obstetrics and gynecology at New York University School of Medicine. "When aromatase inhibitors first came out and were tested, it was stage 3 and 4 women. Survival was clearly better than with tamoxifen. Now they're giving it to all these women with stage 1 and stage 0 cancer, who are likely to be cured, and they have no long-term data."
In fact, the authors of the review stated, women treated with aromatase inhibitors often experienced joint pain and musculoskeletal aching, sometimes so severely they had to discontinue treatment.
There is ample evidence to suggest that estrogen affects pain, the article stated.
For instance, many women have elevated pain thresholds when they are pregnant, a time when estrogen levels are high. Pain perception also fluctuates in women while they are menstruating.
In clinical studies, women treated with aromatase inhibitors have shown higher rates of joint pain compared to women taking a placebo or tamoxifen, the review authors said.
For the most part, the authors reported, this pain has not been disabling although one study reported four women who had to discontinue treatment because of the pain. When the aromatase inhibitor was stopped, the pain went away.
Older women tend to have more of this kind of pain, suggesting that hormonal changes in the postmenopausal period have an effect. And Asian women in the United States going through menopause apparently have lower estrogen levels than white women (this may be due to the fact that they have less fat tissue, a major source of estrogen). At the same time, these Asian women seem to be more susceptible to "menopausal arthritis," the article stated.
A solution to the problem may prove elusive.
"I'm not sure what's to be done," Felson said. "Based on some of these studies, it's clear that anti-inflammatory medications are not going to be enough. This may be the main limiting factor in terms of ability to take these medications, which is a concern. I'm not sure how that plays out, but it is something we need to be familiar with."
More information
The National Cancer Institute has more on aromatase inhibitors.
