The pooled data of the subanalysis confirmed a significant correlation between BRCA1 gene hypermethylation and advanced breast cancer disease stage, (OR = 0.66: 95% CI: 0.50–0.87; p = 0.003, fixed effects model, Figure 3b) as well as a positive correlation with patients’ pre-menopausal status (OR = 1.35: 95% CI: 1.08–1.69; p = 0.009, fixed effects model, Figure 3f), but lymph nodes involvement was not observed to be correlated with BRCA1 hypermethylation (OR = 1.18: 95% CI: 0.97–1.45; p = 0.10, fixed effects model, Figure 3d). Here, BRCA1 is linked to breast cancer.