BACKGROUND: Tumor-infiltrating lymphocyte (TIL) treatment is an individualized method of treating different types of solid tumors by using the immune system of the body to target and destroy cancer cells. Although its usefulness has been shown in certain diseases, such as ovarian cancer and melanoma, research is still being done to see whether it is also beneficial against a wider variety of solid tumors. AIM: To methodically assess the safety, effectiveness, and clinical results of TIL therapy for various solid tumors. METHODOLOGY: A thorough search in various databases produced 218 papers on TIL treatment for various solid tumors (2018-2024). Nine of the ten papers that satisfied the requirements for inclusion in the quantitative analysis were also included in the systematic review. Two reviewers separately extracted the data and evaluated it. The Newcastle-Ottawa Scale and the Cochrane Risk of Bias tool were used to evaluate the quality of the studies, and the I2 statistic in the meta-analysis was used to measure heterogeneity. RESULTS: Numerous studies that looked at the effectiveness of TIL treatment in different types of cancer showed different results. In NSCLC and melanoma, higher CD8+/CD4+ TIL ratios were associated with improved outcomes
in advanced melanoma, TIL therapy was superior to ipilimumab. Response rates differed, with NSCLC showing up at 23.1% and melanoma up to 53.3%. Most studies were of good quality and is confirmed by the Newcastle-Ottawa Scale, while some had problems with follow-up. The results' dependability was confirmed by the ROBINS-I and ROB2 tools, which showed low to moderate bias risk. CONCLUSION: According to the study's findings, TIL therapy is effective in treating solid tumors, especially melanoma, but its results vary according to the kind of cancer as well as tumour microenvironments. Therefore more research is needed to determine the best course of action.