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In the journals: Some side effects of breast cancer treatment may be a good sign

January 01, 2009

In the journals

Some side effects of breast cancer treatment may be a good sign

Side effects are one of the worst aspects of breast cancer treatment. The harsh effects of standard chemotherapy are notorious, but even gentler endocrine treatments, such as tamoxifen, can cause distressing symptoms. These therapies work by interfering with the activity of estrogen, which can fuel the growth of certain tumors. Not surprisingly, the side effects resemble those associated with menopause, when ovarian production of estrogen declines — especially hot flashes, night sweats, and joint pain and stiffness. But as bothersome as such side effects can be, there may be an upside: a study published online and in the Oct. 30, 2008, Lancet Oncology suggests that in some cases they may be a sign that the treatment is working.

In a retrospective analysis of data on 3,964 women treated for early-stage breast cancer in the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial, researchers from the University of London studied the recurrence rate of breast cancer in women who complained of joint pain or vasomotor symptoms (hot flashes, night sweats, and cold sweats) during treatment with either tamoxifen or anastrozole (Arimidex). Tamoxifen works by blocking estrogen at receptor sites on the tumor; anastrozole works by blocking the activity of aromatase, an enzyme important in the production of estrogen in fat and other tissues — the main sources of estrogen in postmenopausal women.

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