Breast cancer is the leading cause of cancer death among Latinas in California. Understanding hereditary cancer risk can help improve screening and detection by identifying women who should start more frequent screening at an earlier age, with more accurate methods. This project aims to better understand which genetic variants cause Latinas to develop breast cancer, and to increase community awareness of hereditary cancer and genetic testing.

Genetic Variants and Risk

The team has identified some previously unknown genetic variants that may contribute to the development of breast cancer in Latinas by examining DNA sequences from over 4,000 Latina women who developed breast cancer, and comparing them to data from over 4,000 Latina women who did not develop breast cancer.

The investigators are using a similar method to refine Latina womens' polygenic risk scores, which take into account all of a person's genetic variants to calculate their risk of developing a particular disease. In addition to using existing databases for their analysis, the project team is also recruiting new women for the study through the California Cancer Registry, which collects information about almost all cancers diagnosed in California.

The COVID-19 pandemic delayed the ability to recruit patients, but Dr. Ziv and his team resumed recruitment in the last half of 2020. In the interim, they built the infrastructure to track recruitment, eligibility, and collection of tissue samples.

Molecular Profiles

In addition to researching the DNA of Latina women and their increased likelihood of developing cancer, the team is also investigating the DNA and RNA profiles of breast tumors from Latinas to make associations between a patient's DNA and the types of breast tumors she may develop. The goal is to find genetic mutations that may be more frequently or even uniquely altered in Latinas. The team is in the process of collecting tumor and blood samples from patients at City of Hope and isolating the DNA and RNA for sequencing.


The project also educates members of the Latina community about hereditary breast and ovarian cancer by training promotoras–community health educators–to teach fundamentals of cancer, genetic heritability, and screening. The project has trained 24 promotoras with in-person and virtual sessions.

The promotoras themselves have educated more than 200 community members, and of those 171 have completed family histories which will allow the investigators to identify those who may benefit from genetic counseling. COVID-19 required the in-person education program shift to a virtual platform, which created a number of challenges including that members of the target communities were sometimes unfamiliar with the technology and required significant assistance from the promotoras. Additionally, many community members either contracted COVID-19 themselves or were caring for someone who had, and their priorities understandably shifted to more immediate health issues. Even so, the promotoras were able to adapt and are now educating women at the originally proposed rate.

Access to Care

Dr. Ziv and his team are also working to assess the policy and economic implications of genetic testing. Use of precision medicine, such as genetic testing, can be limited by health insurance coverage. Latinas in California are more likely than other populations to be insured by Medi-Cal or to be uninsured. The investigators in this study wanted to gather information about current policies and usage to assess possible implications of changes to coverage of genetic tests. The investigators compared access to coverage across four different settings by gathering data from safety net and academic medical centers in both California and North Carolina.

Research Team and Collaborators

Research Team

  • University of California, San Francisco
    • Elad Ziv, MD


  • Bay Area Cancer Connections
  • City of Hope
  • Latino Cancer Institute
  • Pomona Health
  • Stanford University
  • UC Davis
  • Vision y Compromiso
  • Zuckerberg SF General

For More Information

David Reiner, PhD
David Reiner is a Science Officer within the California Initiative to Advance Precision Medicine.