The relationship between the change with neoadjuvant chemotherapy in the tumor-infiltrating lymphocyte (TIL) expressions and pathological response in breast cancer patients.

3114 Background: Many prognostic biomarkers for survival have been studied in the neoadjuvant setting for locally advanced breast cancer (LABC). Our study assessed the correlation between the change in tumour-infiltrating lymphocytes (TIL) before and after neoadjuvant chemotherapy (NAC) in breast tissue and its impact on survival in patients with LABC. Methods: Eighty-four LACB patients were retrospectively analysed in this study. TIL was assessed by means of immunohystochemistry (Eclipse Ni, Nikon, Japan) in paraffin-embedded blocks obtained by core-needle biopsy or surgical specimen with respect to the 'TIL working group' criteria. Results: TIL scores were grouped as 0%, <10%, 10-50%, and >50%, the median TIL percentage was 17.5% before NAC and 5% after NAC, and the difference was statistically significant (p<0.001). Postop-Ki-67 (p=0.005), molecular subtype (p=0.027), pre-NAC TIL score (p=0.006), post-NAC TIL score (p<0.001), postop-Ki-67 (p=0.005) and preoperative residual cancer burden tumour-infiltrating lymphocyte (RCB-TIL) (p<0.001) were significantly correlated with pCR. Higher TIL scores were significantly associated with higher PCR rates. Univariate analysis for disease-free survival (DFS) and overall survival (OS) revealed that postop-Ki-67 level and presence of pCR and postoperative ki-67 score (p=0.031) were significant prognostic factors, respectively. The independent prognostic factor for DFS were postop-Ki-67 score (p=0.012, RR: 6.16, 95% CI: 1.48-9.12), post-NAC TIL score (p=0.041, RR: 0.42, 95% CI: 0.16-1.06) and the presence of pCR (p=0.038, RR: 0.10, 95% CI: 0.01-0.87). Logistic regression analysis showed that a preoperative ki-67 score greater than 14% (p=0.001, OR: 4.55; 95% CI: 0.11-1.49), a postoperative ki-67 score equal to or lower than 14% (p=0.011, OR: 1.10; 95% CI: 0.42-2.29), preop-grade 3 (p=0.01, OR: 2.65; 95% CI: 0.85-3.14), low postop-TIL score (p<0.001, OR: 3.14; 95% CI: 0.79-4.11) were significant predictive factors for pCR. Conclusions: Our study confirms the hypothesis that TIL expressions may be therapeutic targets, especially in specific molecular breast cancer subtypes.