CD8A and breast carcinoma: Based on the heterogeneity test, the random-effects model was used to calculate the combined MD and 95% CI, which were 0.35 (0.14–0.56), P = 0.001, indicating that there is a statistically significant difference between two groups, which explains that SFI combined with chemotherapy can significantly improve the expression level of CD4+/CD8+ in the treatment of breast cancer.