SIRT6 and breast cancer: As shown in Fig. 2B, we conducted a subgroup analysis by cancer type, which revealed that low SIRT6 expression was significantly associated with better overall survival in breast cancer (HR = 0.49, 95% CI = 0.27–0.89, P = 0.179) and other system cancer (OS and OC) (HR = 0.30, 95% CI = 0.10–0.91, P = 0.069), but not in non-small cell lung cancer, hepatobiliary and pancreatic cancer.