The field of breast cancer research has reached a significant milestone with the global adoption of a standardized method for assessing tumor-infiltrating lymphocytes (TILs), marking a decade of transformative progress in cancer diagnostics and prognostication.
Distinct TILs Patterns Across Breast Cancer Subtypes
Dr. Roberto Salgado, anatomic pathologist at Institut Jules Bordet in Antwerp, Belgium, presented comprehensive findings at the San Antonio Breast Cancer Symposium 2024, highlighting how TILs manifestation varies across different breast cancer subtypes.
Triple-negative breast cancer, characterized by the absence of hormone receptors and HER2, has yielded the most extensive TILs data. "Most of the information that we already have on TILs is based on that tumor type," explains Dr. Salgado, noting that this knowledge is beginning to inform treatment decisions.
HER2-positive breast cancer represents the second most significant category for immune system involvement. Research has demonstrated TILs' prognostic value in predicting cancer recurrence, though therapeutic applications remain under investigation.
For hormone receptor-positive breast cancer, researchers are still uncovering the immune system's role, with new data expected in 2025 to further illuminate this relationship.
Standardization Success and Global Implementation
The International Immuno-Oncology Biomarker Working Group's standardized TILs assessment method, established a decade ago, has achieved remarkable global acceptance. "There is no analysis of TILs worldwide that is not using the method that the working group has developed," Dr. Salgado emphasizes.
This standardization has enabled unprecedented international collaboration, as evidenced by a recent landmark study published in JAMA. The research successfully integrated TILs data from multiple countries, including Japan, South Korea, European nations, and the United States, analyzing thousands of patients using consistent methodology.
Clinical Impact and Future Directions
The standardized approach has significantly enhanced the accuracy and consistency of TILs assessments, improving prognostic capabilities and potentially influencing treatment decisions. While the clinical application varies by breast cancer subtype, the methodology's stability has been crucial for advancing its integration into daily clinical practice.
For triple-negative breast cancer, clinicians are beginning to utilize TILs information for treatment planning. In HER2-positive cases, while prognostic value is established, therapeutic applications are still being developed. The hormone receptor-positive subtype represents the next frontier for understanding TILs' clinical significance.
