The TILs-US score on ultrasonography can predict the pathological response to neoadjuvant chemotherapy for human epidermal growth factor receptor 2-positive and triple-negative breast cancer

Background: The tumor-infiltrating lymphocyte (TIL)-ultrasonography (US) score determined through characteristic US findings has predictive performance of lymphocyte-predominant breast cancer (LPBC). This study aimed to investigate whether the TIL-US score before neoadjuvant chemotherapy (NAC) can predict the pathological complete response (pCR).

Methods: We evaluated patients with human epidermal growth factor receptor type 2 (HER2)-positive breast cancer (n = 55) and triple-negative breast cancer (TNBC) (n = 24) who underwent surgery after NAC from November 2012 to April 2019. Pre-NAC biopsy examination was performed to examine stromal TILs; the cutoff value for predicting pCR was defined as ≥50% stromal TILs. The TILs-US score was calculated from the pre-NAC US findings. Based on previous data, the cutoff value for predicting pCR was set at ≥4 points.

Results: Forty-six patients achieved pCR. The TIL-US score was significantly associated with the pCR rate (p = 0.003) but not the pre-NAC biopsy findings (p = 0.055). Multivariate logistic regression analysis revealed that a TILs-US score ≥4 and HER2 positivity were significant pCR predictors (odds ratio [OR] 3.69; p = 0.031; OR 8.74; p = 0.025).

Conclusions: TILs-US scores can be used to evaluate the therapeutic effect of NAC, and may be used as a non-invasive, convenient, and an alternative method to assess stromal TILs in pre-treatment biopsies.