Fertility Preservation Using Tamoxifen and Letrozole in Estrogen Sensitive Tumors Trial (TALES)
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ClinicalTrials.gov Identifier: NCT03011684 |
Recruitment Status :
Recruiting
First Posted : January 5, 2017
Last Update Posted : May 3, 2022
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Condition or disease | Intervention/treatment | Phase |
---|---|---|
Infertility | Drug: Tamoxifen Drug: Letrozole | Phase 3 |

Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 144 participants |
Allocation: | Randomized |
Intervention Model: | Single Group Assignment |
Masking: | None (Open Label) |
Primary Purpose: | Treatment |
Official Title: | Fertility Preservation Using Tamoxifen and Letrozole in Estrogen Sensitive Tumors Trial |
Actual Study Start Date : | July 21, 2016 |
Estimated Primary Completion Date : | January 31, 2023 |
Estimated Study Completion Date : | January 31, 2023 |
Arm | Intervention/treatment |
---|---|
Experimental: ER Positive - Letrozole |
Drug: Letrozole
For ER Positive Randomization |
Experimental: ER Positive - Tamoxifen |
Drug: Tamoxifen
For ER Positive Randomization |
No Intervention: ER Negative |
- Mature Oocyte Yield [ Time Frame: Up to 2 weeks ]To determine if the assigned stimulation regimen will result in a difference in mature (meiosis II) oocyte yield in patients with breast cancer who undergo ovarian stimulation for fertility preservation. An Effect Size of 3 mature oocytes, based on clinically significant difference of 2 embryos to transfer. An average of 2 embryos are transferred per freeze-thaw cycle. If ~75% of mature oocytes will become embryos that can be frozen, then 3 mature oocytes should yield ~2 embryos for transfer. This effect size would effectively mean an additional event of embryos transferred.
- Compare change in estrogen levels during the ovarian stimulation cycle [ Time Frame: Up to 2 weeks ]Estrogen level data will be collected at baseline and after completion of the stimulation cycle
- Compare change in progesterone levels during the ovarian stimulation cycle [ Time Frame: Up to 2 weeks ]Progesterone level data will be collected at baseline and after completion of the stimulation cycle
- Compare change in androgen levels during the ovarian stimulation cycle [ Time Frame: Up to 2 weeks ]Androgen level data will be collected at baseline and after completion of the stimulation cycle
- Compare change in estrogen in follicular fluid [ Time Frame: Up to 2 weeks ]Estrogen levels in follicular fluid will be collected at baseline and after completion of the stimulation cycle
- Compare change in letrozole in follicular fluid [ Time Frame: Up to 2 weeks ]Letrozole levels in follicular fluid will be collected at baseline and after completion of the stimulation cycle
- Compare change in tamoxifen in follicular fluid [ Time Frame: Up to 2 weeks ]Tamoxifen levels in follicular fluid will be collected at baseline and after completion of the stimulation cycle
- Compare duration of stimulation (days) and total gonadotropin dose [ Time Frame: Up to 2 weeks ]
- Number if competent oocytes on day 3 of embryo culture [ Time Frame: Up to 2 weeks ]To assess embryo quality, if applicable, on day 3 of embryo culture, a measure of the developmental competence of the oocytes.
- Number if competent oocytes on day 5 of embryo culture [ Time Frame: Up to 2 weeks ]To assess embryo quality, if applicable, on day 5 of embryo culture, a measure of the developmental competence of the oocytes.

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Ages Eligible for Study: | 18 Years to 50 Years (Adult) |
Sexes Eligible for Study: | Female |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
- New breast cancer diagnosis
- Has not yet begun chemotherapy
- Desires to undergo ovarian stimulation and oocyte retrieval prior to cancer treatment
- Age 18 years old or greater
Exclusion Criteria:
- Chemotherapy has already commenced or been completed
- History of recurrent breast cancer (with a prior history of chemotherapy)
- Stage IV breast cancer diagnosis (metastases remote from the breast)
- Patient's oncologist advises against the trial - in which case they can choose to receive stimulation with letrozole+gonadotropin
- Does not plan to undergo ovarian stimulation and oocyte retrieval prior to diagnosis
- Any significant concurrent disease, illness, or psychiatric disorder that would compromise patient safety or compliance, interfere with consent, study participation, follow-up, or interpretation of study results
- Age less than 18 years old

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03011684
Contact: Ange Wang, MD | 415-353-7475 | Ange.Wang@ucsf.edu |
United States, California | |
University of California at San Francisco | Recruiting |
San Francisco, California, United States, 94143 | |
Contact: Ange Wang, M.D. 415-353-7475 Ange.Wang@ucsf.edu | |
Principal Investigator: Mitchell Rosen, M.D. |
Principal Investigator: | Mitchell Rosen, MD | University of California, San Francisco |
Responsible Party: | University of California, San Francisco |
ClinicalTrials.gov Identifier: | NCT03011684 |
Other Study ID Numbers: |
TALES Trial NCI-2017-01809 ( Registry Identifier: NCI Clinical Trials Reporting Program (CTRP) ) 16751 ( Other Identifier: University of California, San Francisco ) |
First Posted: | January 5, 2017 Key Record Dates |
Last Update Posted: | May 3, 2022 |
Last Verified: | April 2022 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
Product Manufactured in and Exported from the U.S.: | No |
Fertility Preservation Breast Cancer |
Infertility Tamoxifen Letrozole Antineoplastic Agents Aromatase Inhibitors Steroid Synthesis Inhibitors Enzyme Inhibitors Molecular Mechanisms of Pharmacological Action |
Estrogen Antagonists Hormone Antagonists Hormones, Hormone Substitutes, and Hormone Antagonists Physiological Effects of Drugs Antineoplastic Agents, Hormonal Selective Estrogen Receptor Modulators Estrogen Receptor Modulators Bone Density Conservation Agents |