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Xavier Llor, MD, PhD

Genetics, Gastroenterology
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Patient type treated
Child, Adult
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Xavier Llor, MD, PhD, is a gastroenterologist at Yale Medicine with a specialty in gastrointestinal cancer genetics and colorectal cancer. He is the co-director of the Smilow Cancer Genetics and Prevention Program, associate director for cancer screening at the Center for Community Engagement and Health Equity at Yale Cancer Center, and the medical director of the Colorectal Cancer Prevention Program. 

After receiving a medical school education from the Autonomous University in Barcelona, Dr. Llor trained in basic research and internal medicine at the University of Chicago and completed his PhD in molecular biology from the University of Barcelona. Dr. Llor completed his GI fellowship at the University of Illinois at Chicago. His background as both a clinician and researcher led him to specialize in cancer genetics, where he works to identify specific genes that make a person more susceptible to gastrointestinal cancers. “One of the most rewarding things about this field is that every day we seem to discover more, and that knowledge is translated very quickly into patients’ lives,” says Dr. Llor.

As a physician, Dr. Llor uses his research to better care for his patients. The goal is to identify cancer risk as early as possible. This knowledge can help patients take measures to prevent cancer, or it can help doctors treat patients with cancer as early as possible. “The earlier a cancer is detected, the better the prognosis is,” says Dr. Llor. 

In addition, genetic defects that are linked to gastrointestinal cancers may also be linked to cancers in other parts of the body. “We take a broad and comprehensive approach to patients in making sure that we prevent all cancers that are linked to those particular genetic defects,” says Dr. Llor.

As a researcher, Dr. Llor continues to identify new genetic defects that may be linked to colorectal and other GI cancer risk. Furthermore, he is exploring different approaches that lead to a wider identification of these diseases, with a particular emphasis in disseminating this specialized care among the underserved. He has made important contributions to the field of Lynch syndrome (a hereditary form of colorectal cancer). 

Dr. Llor is a professor of medicine (digestive diseases) at Yale School of Medicine.


  • Professor of Medicine
  • Associate CEHE Director for Cancer Screening, Smilow Cancer Hospital
  • Medical Director, Cancer Screening and Prevention Program, and Colorectal Cancer Prevention Program
  • Co-Director, Cancer Genetics and Prevention Program

Education & Training

  • PhD
    University of Barcelona, Molecular Biology (1999)
  • Fellowship
    University of Illinois (1997)
  • Residency
    Lutheran General Hospital-University of Chicago Program C (1994)
  • MD
    University of Barcelona (1986)

Languages Spoken

  • Català (Catalan)
  • English
  • Español (Spanish)

Additional Information

  • Cancer Genetics and Prevention Program
    Yale New Haven Hospital Saint Raphael Campus
    1450 Chapel Street, Ste 107/109
    New Haven, CT, 06511
  • Gastrointestinal Cancers Program
    Smilow Cancer Hospital at Yale New Haven
    35 Park Street
    New Haven, CT, 06511