Introduction: Since an increasing number of patients with BC are treated with NAC, the identification of a biomarker to predict the probability of pCR in certain patients would be transcendental. Previous studies have shown the association of high levels of TILs with a higher rate of pCR in the context of NAC.

Objective: to evaluate the TILs as a predictive factor of response to neoadjuvant treatment.

Results: N=34. In 41% of patients with “low” TILs on core biopsy, a pathological response with extensive residual disease, or chemoresistance, was observed. While in those classified as "high" TILs, 75% of patients had a complete pathological response (p=0.001). In the analysis by molecular subtype, there were no statistically significant differences.

Conclusion: The presence of high TILs in core biopsy of primary breast cancer tumor could be a predictive biomarker of complete pathological response in breast cancer. However, more research is required to determine its clinical utility, mainly in luminal tumors.

TBA