Stromal Tumor Infiltrating Lymphocytes (TIL) as a potential prognostic biomarker for recurrence in Locally Advanced Breast Cancer (LABC) patients

Background: Tumor-infiltrating lymphocytes (TIL) serves as the host adaptive immune response in breast cancer. TIL has the potential to be an independent prognostic factor in breast cancer patients. In this study, we aimed to examine the association between stromal TIL and recurrence in locally advanced breast cancer patients. Methods: A cohort retrospective study was conducted using medical records of female breast cancer patients with locally advanced breast cancer. We collected patients' data, including demographic data from the medical record. Stromal TIL was examined following the recommendations of the International TIL Working Group 2014. Results: 75 samples were included with an average age of 49.5 +/- 8.4. Ductal carcinoma was the most common type histologically (88.0%). Luminal B Her2-negative was the predominant breast cancer subtype (32.0%). There was a significant association between the breast cancer subtype and disease-free survival (P - 0.014). The optimal cut-off to determine the recurrence of breast cancer was 15%. The sensitivity, specificity, PPV, NPV, and accuracy of TIL to predict the 24-month disease-free survival (DFS) were 80.5%, 82.4%, 84.6%, 77.8%, and 81.3%, respectively. Every 10% increase in TIL percentage could raise the DFS by 5.45 months (p=0.001). Patients with high TIL values had higher survival than those with low TIL values.Conclusion: There was a significant correlation between the stromal TIL and the recurrence rate. The pre-therapy stromal TIL percentage can be employed as a potential biomarker to predict breast cancer recurrence, particularly in the first two years.