Background: Breast cancer (BC) is a heterogeneous disease with multiple subtypes. Despite various new treatment strategies, several trials were conducted to improve outcomes, particularly in metastatic BC, due to low survival rates. Previously, BC was not thought to be immunologically active, especially when compared to melanoma. However, a recent study has revealed that the presence of tumor-infiltrating lymphocytes (TILs) in between and surrounding tumor cells may be beneficial, and the increased density of TILs was associated with a better prognosis. We conducted this study to evaluate the prognostic impact of TILs in metastatic BC patients.
Material and Method: One hundred and five patients with metastatic breast cancer were prospectively recruited at the Medical Oncology Department, South Egypt Cancer Institute, in the period from January 2018 to January 2020. The median follow-up duration was 17 months The relationship between TILs and clinicopathological features and survival outcomes in metastatic BC patients was evaluated.
Result: High TILs and ER-negative (p=0.000), Her2/neu overexpression (p=0.000), and triple-negative BC (TNBC) (p=0.031 were found to have statistically significant differences. High TILs had a positive prognostic effect on PFS and OS in patients with TNBC. High TILs were significantly associated with improved PFS in patients with HER2/neu overexpression tumors but had no effect on OS.
Conclusion: There is a strong correlation between hormonal and Her2/neu status of BC and TILs density. High TILs density has favorable outcomes regarding OS and PFS, particularly in TNBC in metastatic cases.
Trial registration: South Egypt Cancer Institute ethics committee, SECI-IRB, number IORG0006563-468