GIVE TAMOXIFEN ONLY TO WOMEN WHOSE BREAST CANCER IS ESTROGEN RECEPTOR POSITIVE

Extensive research show that tamoxifen helps to prevent recurrence of a breast cancer after treatment. However, doctors do not know how tamoxifen affects the other apparently healthy breast. Women who have breast cancer are at increased risk for having a new cancer start by itself in the other non-affected breast. Breast cancers are classified into estrogen receptor positive and negative depending on whether the surface of breast cancer cells contains specific binding sites for estrogen to attach. Testing breast cancer for estrogen receptor positive or negative is fairly routine.

Tamoxifen prevents a new breast cancer from forming in the unaffected breast of women whose original breast cancer is estrogen receptor positive and tamoxifen increases risk for a new primary breast cancer in women whose breast cancer is estrogen receptor negative.

Tamoxifen therapy for primary breast cancer and risk of contralateral breast cancer. Journal of the National Cancer Institute, 2001, Vol 93, Iss 13, pp 1008-1013. CI Li, KE Malone, NS Weiss, JR Daling Conclusions: Tamoxifen use appears to decrease the risk of ER-positive contralateral breast tumors, but it appears to increase the risk of ER-negative contralateral tumors. Address Li CI, Fred Hutchinson Canc Res Ctr, Div Publ Hlth Sci, 1100 Fairview Ave N, MP 381, POB 19024, Seattle,WA 98109 USA

Reported 7/25/01; checked 9/3/05

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