Correlation Between Tumor-infiltrating Lymphocytes and Response to Systemic Therapy in Breast Cancer

Neoadjuvant chemotherapy is widely used in patients with early breast cancer to reduce tumor size and improve surgical outcomes. Achieving a pathological complete response (pCR) is associated with improved prognosis; however, reliable predictive biomarkers are still limited. Recent evidence suggests that immune cells in the tumor microenvironment may influence treatment response. This study evaluates immune-related tumor stroma factors (including tumor-infiltrating lymphocytes and immune marker profiles) in tumor tissue obtained prior to treatment. In parallel, circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) are assessed from peripheral blood samples collected before neoadjuvant chemotherapy, after completion of treatment, and during follow-up. The primary objective is to determine whether immune-related tumor stroma factors correlate with pCR after neoadjuvant chemotherapy. Secondary objectives include evaluating the association of immune-related factors with the presence of CTCs and ctDNA and assessing their prognostic value for disease progression and recurrence.