My mother has had surgery for breast cancer and underwent radiation treatments, which she dealt with well. She is now on medication called tamoxifen and gaining weight. I am worried because the weight gain doesn't seem to be leveling off. She has many other health conditions, such as high blood pressure, diabetes and an enlarged heart. Her diabetes is controlled by diet and insulin, so she isn't cheating and eating things she shouldn't. Should I be concerned?

H.W.

Tamoxifen is often given to prevent a recurrence of breast cancer following breast-sparing surgery. Raloxifene (Evista) is another drug in the same class as tamoxifen. Used as a means of preventing osteoporosis, it is being studied to see if it is as effective as tamoxifen in preventing breast cancer recurrence.

Weight gain, while not listed as a side effect, does seem to be associated with tamoxifen. I do not base this statement on any scientific evidence, but merely on observation of patients of mine who are on it -- and my mother. Like your mom, my mom has breast cancer (one year out and doing well after lumpectomy, radiation and tamoxifen) and she, too, has gained weight. She swears the only thing different in her life is the tamoxifen, not eating or exercise habits. Unfortunately, raloxifene will probably have the same effect.

Your mother should talk to her doctors -- both her oncologist and her internist -- about ways to manage her weight gain, and the pros and cons of continuing tamoxifen. The reduction in risk of recurrent breast cancer is significant, so tamoxifen should not be stopped without a long, thoughtful discussion with her doctors.