NCT03011684 · University of California, San Francisco
Fertility Preservation Using Tamoxifen and Letrozole in Estrogen Sensitive Tumors Trial
(TALES)
What this study is about
Latrogenic infertility as a result of cancer treatment has a profound effect on long-term quality of life in survivors of reproductive-age cancers. Oocyte cryopreservation prior to cancer treatment has been associated with improved quality of life, with a potential ability to reduce long-term decision-related regret in cancer survivors.
View original scientific description
Latrogenic infertility as a result of cancer treatment has a profound effect on long-term quality of life in survivors of reproductive-age cancers. Oocyte cryopreservation prior to cancer treatment has been associated with improved quality of life, with a potential ability to reduce long-term decision-related regret in cancer survivors. Though letrozole plus gonadotropin and and tamoxifen plus gonadotropin are currently routinely used worldwide in ovarian stimulation cycles for fertility preservation in patients with estrogen-receptor-positive breast cancer, it is not clear which of the two might lead to improved oocyte yield. Improved knowledge about the efficacy of these medications, with regard to oocyte yield, has the potential to significantly improve quality of life in reproductive-age breast cancer survivors.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
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
Where
- San Francisco, California
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 4, 2026 · Source of record for eligibility and locations