Clinical Scorecard: Dynamics of Tumor-Infiltrating Lymphocytes as Indicators of Neoadjuvant Therapy Response in Luminal Breast Cancer
At a Glance
Category
Detail
Condition
Hormone receptor–positive/HER2-negative (HR+/HER2−) luminal breast cancer
Key Mechanisms
Tumor-infiltrating lymphocytes (TILs) reflect host immune response; dynamic changes in stromal TILs during neoadjuvant chemotherapy (NAC) may indicate treatment response
Target Population
Patients with HR+/HER2− breast cancer undergoing neoadjuvant chemotherapy
Care Setting
Oncology clinics providing neoadjuvant chemotherapy and surgical management
Key Highlights
TILs are established predictive biomarkers in triple-negative and HER2-positive breast cancer but less defined in HR+/HER2− subtype.
HR+/HER2− tumors are immunologically 'cold' with lower TIL infiltration and reduced chemosensitivity.
Dynamic changes in TIL levels (delta-TIL) during NAC may provide additional prognostic information beyond baseline TIL levels.
Guideline-Based Recommendations
Diagnosis
Assess stromal TILs as percentage of stromal area occupied by mononuclear inflammatory cells within invasive tumor, per International TILs Working Group recommendations.
Evaluate TILs both pre-treatment (core biopsy) and post-treatment (surgical specimen) to calculate delta-TIL.
Management
Consider neoadjuvant chemotherapy in selected high-risk HR+/HER2− patients, especially luminal B subtype, for surgical downstaging and in vivo response assessment.
Use pathological complete response (pCR) and residual tumor burden as indicators of treatment efficacy, noting pCR prognostic value is less consistent in HR+/HER2− disease.
Monitoring & Follow-up
Monitor changes in stromal TIL levels before and after NAC to gain insight into tumor-immune interactions and potential treatment response.
Use progression-free survival (PFS) as a key outcome measure post-surgery.
Risks
Recognize that HR+/HER2− tumors have lower immune infiltration and may show limited response to chemotherapy compared to more immunogenic subtypes.
Interpret TIL levels and dynamics cautiously given current evidence is limited and inconsistent regarding prognostic significance.
Patient & Prescribing Data
87 patients with HR+/HER2− breast cancer receiving neoadjuvant chemotherapy followed by surgery
Baseline and dynamic TIL assessments may help predict pathological response and progression-free survival; however, clinical utility requires further validation.
Clinical Best Practices
Perform standardized stromal TIL quantification on pre- and post-treatment specimens following international guidelines.
Incorporate TIL dynamics (delta-TIL) analysis into pathological evaluation to enhance prognostic assessment.
Use multidisciplinary approach integrating clinical, pathological, and immunological data for treatment planning in HR+/HER2− breast cancer.
