Raloxifene is associated with less side effects than tamoxifen in women with early breast cancer: a questionnaire study from one physician's practice.

OBJECTIVE: Selective estrogen receptor modulators (SERMs) are being used increasingly for the prevention and treatment of breast cancer. The currently available SERMs, tamoxifen and raloxifene, are both associated with antiestrogenic side effects that can be bothersome. However, no data exist on how they compare in this regard. We conducted a retrospective, questionnaire-based study to answer this question.

METHODS: Women with early breast cancer in one physician's practice who had received either or both of these drugs were surveyed using a self-administered questionnaire. Respondents graded the frequency and severity of side effects related to estrogen deprivation, such as vaginal dryness, mood changes, hot flashes, weight gain, and changes in libido, as well as other side effects, such as vaginal discharge. They were separated into three groups for analysis (group 1, tamoxifen only; group 2, raloxifene only; group 3, both drugs). Side effects graded 4 or 5 (or weight gain >10 pounds) were considered severe.

RESULTS: Two hundred sixty-four questionnaires were available for analysis. Women on raloxifene had a shorter average duration of therapy. In comparing the tamoxifen and raloxifene groups, vaginal discharge, severe hot flashes, and weight gain of >10 pounds were significantly more frequent with tamoxifen. However, weight gain was also related to the duration of therapy with either drug.

CONCLUSIONS: In this observational study, antiestrogenic side effects were common with either tamoxifen or raloxifene. Raloxifene is associated with significantly less vaginal discharge and severe hot flashes than tamoxifen in women with early breast cancer. Although weight gain of >10 pounds may also occur less frequently on this drug, this may be confounded by the shorter average duration of raloxifene therapy.