When Hot Flashes Are Good News

Oct. 30, 2008— -- No one likes the side effects of chemotherapy. But would your attitude change if you knew that the side effects might predict success with your treatment for cancer?

A study in today's issue of Lancet Oncology describes just such a finding in women with breast cancer treated with either tamoxifen or anastrozole as part of an adjuvant (preventive) treatment clinical trial.

Women who participated in the trial had been diagnosed and treated for primary breast cancer. In this study, the researchers examined the records of women who then received either anastrozole or tamoxifen to prevent the breast cancer from returning.

If a woman was treated with anastrozole or tamoxifen and developed vasomotor symptoms -- night sweats, hot flashes and sweating -- and/or joint pain after they started their medicine, then the chances that their breast cancer would return were lower than for a woman who did not develop either symptom.

The researchers can't explain why this happened. They suggested it might be related to a woman's genetic profile and how her body processed the medications, but that isn't for certain.

The end result was that, if a woman had vasomotor (usually called menopausal) symptoms, the chance that her breast cancer would return was decreased by about 16 percent. If she developed joint symptoms, the recurrence rate was reduced by about 41 percent. And, if she had both symptoms occur after treatment, the odds of recurrence were decreased by about 47 percent.

Both anastrozole and tamoxifen decrease the effects of estrogen in post-menopausal women with breast cancer, although they work differently.

Tamoxifen is an estrogen blocker and blocks the effect of circulating estrogen on breast cancer cells in post-menopausal women whose cancers are hormone sensitive. Anastrozole works by decreasing the amount of estrogen circulating in the body substantially. (You may be surprised to learn that there is estrogen in women who are post-menopausal. For example, fat cells in post-menopausal women are a source of estrogen -- a low level source to be sure, but a source, nonetheless.)