PhD Scientific Days 2024

Pathological and Oncological Sciences I.

Digital Image Analysis for Evaluating Stromal Marker Expression in Triple Negative Breast Cancer

Text of the abstract

Introduction: A growing body of research supports the role of the tumor microenvironment in tumor progression and the development of certain therapeutic resistances. In triple-negative breast cancer (TNBC), few effective biomarkers are available, so objective assessment of stromal characteristics using conventional and digital image analysis (DIA) methods may be crucial.

Methods: H&E stained surgical specimens of 105 patients diagnosed with TNBC, treated by primary surgery between 2005-2013 were analyzed. Tumor stroma ratio (TSR) and overall stromal extent was determined on digitized H&E stained sections according to the recommendations of Mesker et al. visually and utilizing DIA (3D Histech, Quantcenter). The dominant stromal type of tumors (collagen (C), lymphocyte (L), fibroblast (F) dominant) based on the recommendations of Ahn S. et al. was also determined. Immunohistochemistry was performed on tissue microarrays (TMA) to estimate the Col-1, Col-3, and Fibrillin proteins. The intensity and percentage of positivity was evaluated visually and by using DIA.

Results: Intra- and interobserver variability of TSR and overall stromal extent was low (ICC=0.99; κ=0,83). DIA and visual analysis showed significant correlation in both H&E stained surgical specimens and immunostained TMA samples, except for immunohistochemical intensity measurements (κ=0.42). TSR and overall stroma extent were significantly associated with several variables, such as mitotic index, age, tumor size, and number of metastatic lymph nodes. Significantly different TSR values were detected in the tumors presenting with distinct stromal type (p=0.0017): L<F<C. Based on Kaplan-Meier analyses overall and progression free survival correlated significantly with the overall stromal extent, as stroma-high tumors had a worse prognosis (PFS: p=0.042, OS: p=0.027).

Conclusion: DIA can be quickly and easily applied in routine pathology in H&E stained sections to quantify tumor stroma, which is more and more considered as an important parameter in treatment decision and prognosis. Stroma-high TNBC tumors are characterized by significantly worse survival.

Abbreviations: DIA: digital image analysis; H&E: hematoxylin & eosin staining; OS: overall survival; PFS: progression-free survival; TMA: tissue microarray; TNBC: triple negative breast cancer; TSR: tumor stroma ratio