The prognostic value of tumor-infiltrating T lymphocytes in ovarian cancer

The prognostic value of tumor-infiltrating lymphocytes (TILs) in ovarian cancer is still in controversial. This study is aimed to assess the impact of different TIL subsets on the progression free survival (PFS)/disease free survival (DSS) and overall survival (OS)/disease specific survival (DSS) in ovarian cancer. A comprehensive literature search in PubMed, ISI Web of Science, and Medline was performed to identify relevant studies evaluating the prognostic value of TILs in ovarian cancer. Reviews of each study were conducted and data were extracted. The main outcomes analyzed were PFS/DFS and OS/DSS. A total of 21 eligible studies enrolling 2903 ovarian cancer patients were included for the meta-analysis. The overall analysis revealed that intraepithelial CD3(+) and CD8(+) TILs were strongly associated with improved PFS/DFS (HR=0.53, for CD3(+) TILs; and HR=0.50, for CD8(+) TILs). Intraepithelial CD8(+)/Foxp3(+) ratios appeared to be associated with improved PFS, though without reaching statistical significance (HR=0.73). Moreover, intraepithelial CD3(+), CD8(+), and CD103(+) TILs were clearly associated with increased OS/DSS (HR=0.50, for CD3(+) TILs; HR=0.62, for CD8(+) TILs; HR=0.54, for CD103(+) TILs). However, intraepithelial FoxP3(+) TILs, CD8(+)/FoxP3(+) ratios, CD8(+)/CD4(+) ratios, and stromal TILs had no impact on the OS/DSS (HR=0.98, for FoxP3+ TILs; HR=0.69, for CD8(+)/FoxP3(+) ratios; HR=0.48, for CD8(+)/CD4(+) ratios; HR=0.82, for stromal TILs). In conclusion, the present meta-analysis supports the hypothesis that intraepithelial TILs are predictive biomarkers for the prognosis of ovarian cancer patients. Future randomized studies are needed to verify these observations.