Hot Spot and Whole-Tumor Enumeration of CD8 + Tumor-Infiltrating Lymphocytes Utilizing Digital Image Analysis Is Prognostic in Triple-Negative Breast Cancer
McIntire PJ., Irshaid L., Liu Y., Chen Z., Menken F., Nowak E., Shin SJ., Ginter PS.
CD8 + tumor-infiltrating lymphocytes (TIL) are prognostic and predictive in triple-negative breast cancer (TNBC). There is debate surrounding TIL enumeration methodology (whole tumor vs. hot spot). TILs were enumerated in 76 TNBC cases. Hot spots were equivalent to whole tumor for TNBC prognostication. Hot spots may serve as an alternative to whole-tumor evaluation for CD8 + TIL enumeration in future studies and clinical practice. Background: CD8 + tumor-infiltrating lymphocytes (TILs) have emerged as a prognostic indicator in triple-negative breast cancer (TNBC). There is debate surrounding the prognostic value of hot spots for CD8 + TIL enumeration. Methods: We compared hot spot versus whole-tumor CD8 + TIL enumeration in prognosticating TNBC using immunohistochemistry on whole tissue sections and quantification by digital image analysis (Halo imaging analysis software; Indica Labs, Corrales, NM). A wide range of clinically relevant hot spot sizes was evaluated. Results: CD8 + TIL enumeration was independently statistically significant for all hot spot sizes and whole-tumor annotations for disease-free survival by multivariate analysis. A 10× objective (2.2 mm diameter) hot spot was found to correlate significantly with overall survival (P =.04), while the remaining hot spots and whole-tumor CD8 + TIL enumeration did not (P >.05). Statistical significance was not demonstrated when comparing between hot spots and whole-tumor annotations, as the groups had overlapping confidence intervals. Conclusion: CD8 + TIL hot spot enumeration is equivalent to whole-tumor enumeration for prognostication in TNBC and may serve as a good alternative methodology in future studies and clinical practice.