Pain Makes Some End Breast Cancer Drug
Joint and Bone Pain Forces Some Women to Stop Taking Aromatase Inhibitors
Sept 6, 2007 -- Nearly half of women on certain antiestrogen drugs that can
help keep breast cancer at
bay develop aches and pains so severe that the women stop taking their
medication, a new study suggests.
The drugs, known as aromatase inhibitors, block an enzyme the body uses to
make estrogen, which fuels some breast cancers. Given after surgery,
chemotherapy, or radiation therapy, the drugs substantially slash the risk of
"We were surprised at the large number of women who stopped taking the
drugs due to musculoskeletal symptoms," says N. Lynn Henry, MD, PhD, a
lecturer in internal medicine at the University of Michigan Medical School in
"Only 15% of patients in other studies stopped taking aromatase
inhibitors for any side effect and here we have nearly 15% dropping out
because of musculoskeletal problems alone," she tells WebMD.
Drug Side Effects
Overall, 23% of the women in the new study given one of two aromatase
inhibitors -- Aromasin or Femara -- stopped taking their drugs due to side
effects, which also included hot flashes and nausea, Henry says.
Henry says that most women told their doctor about the problem and were
switched to a different aromatase inhibitor or tamoxifen, an older antihormone
"At least with the very small numbers we have at this point, the women
seem to be tolerating the new drug after the switch," she adds.
Henry presented the findings in San Francisco, at the 2007 Breast Cancer
Symposium, co-sponsored by the American Society of Clinical Oncology and four
other cancer care societies.
The study included 100 postmenopausal women on Aromasin or Femara who filled
out questionnaires asking about pain and difficulty with daily activities.
Forty-two percent of the women reported serious bone and joint problems,
such as severe pain or difficulty opening a jar, and were referred for
evaluation by a rheumatologist. The symptoms struck an average of two months
after they started taking the drug.
Among the 38 women evaluated to date, the most common side effects were
rotator cuff tendonitis, carpal tunnel syndrome, and osteoarthritis.
The researchers did not compare the rate of side effects between Aromasin
Henry says that there does not seem to be any way, at least at this point,
to predict who will develop serious aches and pains. Results showed that older
women are as susceptible as younger ones, and overweight women as susceptible
as thinner women.
Aromatase Inhibitors Still Drugs of Choice
Julie R. Gralow, MD, an associate professor of medical oncology at the
University of Washington School of Medicine and moderator of a press briefing
on the findings, says that at least for now, the findings should not deter
doctors from recommending aromatase inhibitors.
"Tamoxifen is a good drug, but it also has side effects, and the
aromatase inhibitors have consistently been shown to improve survival compared
with tamoxifen alone," she tells WebMD.