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Study of Tamoxifen and Ovarian Aging Needs Participants

Little known about impact on ovaries of common treatment

Trial Starts: June 2011; Trial Ends: June 2014

Written By Robin Warshaw, Contributing Writer
Reviewed By Lynn Westphal, MD, FACOG

Hormonal therapy with tamoxifen is standard treatment for pre- and perimenopausal women with hormone receptor-positive breast cancer. Given for up to five years after other treatment, tamoxifen blocks estrogen from reaching estrogen receptors and lowers the chances the breast cancer will come back.

Because tamoxifen is given during the reproductive years, this study looks at its long-term effect on ovarian aging. 

About the Study

Chemotherapy is known to affect the ovaries. Yet researchers know little about whether hormonal, or endocrine, therapy such as tamoxifen has any impact.

The researchers of this study want to see if long-term tamoxifen use influences ovarian aging and age of menopause onset. That knowledge could help younger women make decisions about treatment. According to these researchers, the relationship between hormonal therapy and ovarian function has not been directly studied before.

The study will determine the mean age of menopause in women who completed tamoxifen treatment and compare that to the average age of natural menopause.

The study will also measure biological factors, such as hormone levels and the number of ovarian follicles, to assess overall ovarian function. Those biomarkers will be looked at by ultrasound and blood tests in women who received tamoxifen. The results will be compared to age- and ethnicity-matched women (controls) who have not been treated for breast cancer. 

Participants’ reproductive histories, lifestyle factors, medical histories and demographics will be recorded through surveys.

Who Is Eligible to Participate?

Originally designed for participants from the University of California, San Francisco (UCSF) Cancer Registry treated in 2010 and earlier, the study has now been expanded to include women treated elsewhere.

You may be able to take part if you:

  • are female and age 25 or older;
  • were diagnosed with stage I-III breast cancer or DCIS (ductal carcinoma in situ), or determined to be at high risk for primary breast cancer;
  • completed at least two years of hormonal therapy with either:
    • tamoxifen alone
    • ovarian suppression plus tamoxifen or an aromatase inhibitor
    • ovarian suppression alone;

(those without such treatment will be placed in the control group)

  • were premenopausal at the start of hormonal therapy (you had at least one period in the year before starting treatment).

To be assessed for biomarkers, you must:

  • be off all hormonal therapy—tamoxifen, ovarian suppression with goserelin (Zoladex) or leuprolide (Lupron), or aromatase inhibitor—for at least six months before study enrollment;
  • be off hormone contraceptives, fertility treatments or other hormone therapies for at least three months before enrollment;
  • have had regular periods for the last three months.

You may not participate if you received any chemotherapy before menopause (including for breast cancer treatment) or have a history of ovarian surgery or documented infertility.

Study Location and Activities

This study is taking place at:

  • UCSF Helen Diller Family Comprehensive Cancer Center

San Francisco, California

If you live near the study location, you may fully participate. Local participants will have an ultrasound and blood draw to measure biomarkers, and will complete surveys. Participants from outside the area complete surveys only.

Contact Information

To find out more about this study or participation, contact Erin Duralde at or (415) 353-7672.

For more information, visit


This article was supported by Cooperative Agreement Number DP11-1111 from The Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention.