# Tamoxifen versus letrozole for fertility preservation

Source: https://onco.cc/trials/nct03011684/  
OnCo record `nct03011684` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

This study compares tamoxifen and letrozole during ovarian stimulation before cancer treatment. It asks which approach produces more mature eggs for fertility preservation.

## Summary

This study compares tamoxifen and letrozole during ovarian stimulation before cancer treatment. It asks which approach produces more mature eggs for fertility preservation.

Interventional study registered as NCT03011684, sponsored by University of California, San Francisco. Registry phase: 3. Registry enrollment is 309 participants (estimated). Registry status checked October 10, 2026: recruiting. UCSF lists this study as open to eligible people; local availability and overall registry status are separate. See the registry for full eligibility and current sites.

## Fields

- Kind: Trial
- Status: recruiting
- Last checked: 2026-10-10
- Also known as: Fertility Preservation Using Tamoxifen and Letrozole in Estrogen Sensitive Tumors Trial
- Tags: ucsf-breast-coverage; interventional
- Registry id: NCT03011684
- Phase: 3
- Setting: Fertility preservation before treatment for estrogen-sensitive tumors
- Sponsor: University of California, San Francisco

## Sources

- ClinicalTrials.gov NCT03011684: https://clinicaltrials.gov/study/NCT03011684
- UCSF study listing and local availability: https://clinicaltrials.ucsf.edu/trial/NCT03011684

## Connected records

- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/)
- drugs: [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/), [Tamoxifen](https://onco.cc/drugs/tamoxifen/)
- institutions: [UCSF Helen Diller Family Comprehensive Cancer Center](https://onco.cc/institutions/ucsf/)

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