A systematic review and meta-analysis were conducted to evaluate the prognostic impact of tumour-infiltrating lymphocytes (TILs) in cancer. The study analyzed data from 52 studies involving solid tumours, focusing on CD3+, CD4+, CD8+, and FoxP3+ TILs, as well as ratios between these subsets. The results showed that CD3+ and CD8+ TILs were associated with improved survival outcomes, with hazard ratios (HRs) of 0.58 and 0.71, respectively. In contrast, FoxP3+ regulatory TILs did not show a significant association with overall survival. The CD8+/FoxP3+ ratio had a more pronounced effect on survival, with an HR of 0.48, but was used in relatively few studies. The study emphasized the importance of considering TIL ratios for a more comprehensive understanding of the immune response in cancer. It also highlighted the need for careful study design to avoid overestimating the prognostic significance of TILs. The findings suggest that TILs, particularly CD8+ TILs, may play a role in delaying tumour progression, although the exact mechanisms remain unclear. The study concluded that future research should focus on improving study quality and considering the complex interactions within the tumour microenvironment.A systematic review and meta-analysis were conducted to evaluate the prognostic impact of tumour-infiltrating lymphocytes (TILs) in cancer. The study analyzed data from 52 studies involving solid tumours, focusing on CD3+, CD4+, CD8+, and FoxP3+ TILs, as well as ratios between these subsets. The results showed that CD3+ and CD8+ TILs were associated with improved survival outcomes, with hazard ratios (HRs) of 0.58 and 0.71, respectively. In contrast, FoxP3+ regulatory TILs did not show a significant association with overall survival. The CD8+/FoxP3+ ratio had a more pronounced effect on survival, with an HR of 0.48, but was used in relatively few studies. The study emphasized the importance of considering TIL ratios for a more comprehensive understanding of the immune response in cancer. It also highlighted the need for careful study design to avoid overestimating the prognostic significance of TILs. The findings suggest that TILs, particularly CD8+ TILs, may play a role in delaying tumour progression, although the exact mechanisms remain unclear. The study concluded that future research should focus on improving study quality and considering the complex interactions within the tumour microenvironment.