Statistically significant associations were considered as “positive results” when they met the following criteria [44]: (1) P value < 0.05 was observed in at least one of the two genetic model (individual GSTM1 and GSTT1 polymorphisms with BC risk (there was no need to meet this condition between GSTM1 and GSTT1 polymorphisms and BC risk because they only used null vs. present); (2) FPRP < 0.2; (3) statistical power > 0.8; and (4) I2 < 50%. The gene discussed is GSTM1; the disease is breast cancer.