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Tamoxifen dosage same no matter weight?

Page last modified on: October 13, 2008
Question from Jul: Why is the dose of tamoxifen the same for a woman who weighs 300 pounds and a woman who weighs 115? Have any studies been done on the effectiveness of a lower dose for smaller woman? Thank you!
Answer —Patricia Ganz, M.D.: In the early days of breast cancer treatment with tamoxifen, primarily for women with metastatic disease but later in the adjuvant setting, there were studies that looked at a variation in dose between 20 and 40 mg per day. There have been no studies done looking at lower doses, except for a few select research studies looking at prevention. Like other hormone drugs, doses are often chosen irrespective of weight because of the general hormonal effect, rather than a dose limiting toxicity. When we give chemotherapy, we have a dose that if exceeded, will cause harm to some organs in the body. That is not the case in general with hormones, although there may be some toxicity at high doses. In the studies that were done looking at higher doses, there was no benefit, so the dose is standardized at 20 mg per day.

On Wednesday, August 15, 2007, the Ask-the-Expert Online Conference was called Managing Ongoing MedicationsPatricia Ganz, M.D. and moderator Lillie Shockney, R.N., B.S., M.A.S. answered your questions about staying on track with breast cancer medications you have to take on a regular basis.


The materials presented in these conferences do not necessarily reflect the views of breastcancer.org. A qualified healthcare professional should be consulted before using any therapeutic product or regimen discussed. All readers should verify all information and data before employing any therapies described here.

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Meet the Experts

Patricia A. Ganz, M.D.Patricia A. Ganz, M.D. is a medical oncologist and a professor in the schools of medicine and public health at UCLA, and is director of the division of cancer prevention and control research at the Jonsson Comprehensive Cancer Center there.

Lillie Shockney, RN., BS., M.A.S.Lillie Shockney, R.N., B.S., M.A.S. is the administrative director of the Johns Hopkins Avon Foundation Breast Center.

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