In the subgroup analysis based on ethnicity, the results indicated that ESR1 XbaI (A>G) polymorphism might significantly increase the risk of prostate cancer among African populations (G allele vs. A allele: OR = 1.60, 95%CI: 1.00–2.57, P = 0.049; GG + AG vs. AA: OR = 2.15, 95%CI: 1.12–4.13, P = 0.022; respectively), but not enough reliability was established due to the estimation of effect size from a single study [26]. The gene discussed is ESR1; the disease is Familial prostate cancer.