LEP and cancer: In a subgroup analysis conducted by cancer system, we obtained significant results that the LEP G19A polymorphism decreased the risk of digestive system cancer in three models (allele comparison: OR = 0.937, p = 0.016; recessive comparison: OR = 0.838, p = 0.005; homozygote comparison: OR = 0.863, p = 0.028); we also obtained significant results that the LEP G19A polymorphism decreased the risk of urinary system cancer in three models (allele comparison: OR = 0.881, p = 0.022; dominant comparison: OR = 0.842, p = 0.019; heterozygote comparison: OR = 0.855, p = 0.043) (Table 3 and Figure 2).