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U.S. Food & Drug Administration
Continuing Education and Accreditation
Division of Learning and Organizational Development
Center for Drug Evaluation and Research

Assessment of Stromal Tumor-Infiltrating Lymphocytes

Step Status
Educational Content
Starts On: Wed, 3/1/23: 12:00 AM EST
Ends On: Sun, 3/1/26: 12:00 AM EST
Type: Enduring Material
Credits: 3
Description: Tumor-infiltrating lymphocytes have been established as a prognostic biomarker in early-stage triple negative breast cancer. The assessment of the density of stromal tumor-infiltrating lymphocytes at the time of diagnosis may improve the accuracy of prognosis determination and inform therapeutic decision-making.

Course Content
1. Introduction to stromal tumor-infiltrating lymphocytes: We discuss the immune system's role in mediating tumor progression and the statistics and literature that demonstrate how sTILs are prognostic biomarkers for patient outcomes and response to therapy in certain types of breast cancer.

2. TILs Education: What are TILs and their Assessment: Video description of the steps of the sTILs assessment.

3. Pitfalls in the sTILs Assessment: Discussion of example pitfalls encountered in the sTILs assessment.

4. The evaluation of tumor-infiltrating lymphocytes (TILs) in breast cancer: recommendations by an International TILs Working Group 2014

  • Describe the significance of stromal tumor infiltrating lymphocytes in triple negative breast cancer.
  • Demonstrate knowledge of the approach to determining the density of stromal tumor-infiltrating lymphocytes.

Additional Information:
Activity Announcement With Additional Details




• Additional *interactive training* on sTILs assessment is available from the course instructors. Please email or with "Interactive Training" in the subject line.

• For more information on the research project in which this course was developed (the High-Throughput Truthing project), please visit

• For more information on the sTILs assessment and to get involved with the International Immuno-Oncology Biomarker Working Group on Breast Cancer (the International TILS Working Group), please visit

• This work was supported by the FDA Office of Women's Health. This project was supported in part by an appointment to the ORISE Research Participation Program at the Center for Drugs and Radiological Health, U.S. Food and Drug Administration, administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and FDA/Center. We also acknowledge the Pathology Department of Institut Jules Bordet in Brussels, Belgium for providing the pathology slides for this work.