CD8A and breast cancer: Six trails [27–29, 31, 34, 35] with 498 cases that reported CD8+ meta-analysis showed that there was statistical heterogeneity between studies in terms of the heterogeneity test (χ2 = 62.48, P < 0.00001, I2 = 92%); therefore, the random-effects model was applied to calculate the combined MD and 95% CI, which were 0.21 (−2.81, 3.23), P = 0.89, indicating that there is no statistical difference between two groups, which explains that SFI combined with chemotherapy in the treatment of breast cancer cannot improve the CD8+ expression level.