Serum BDNF level (31,747.4 [23,068.0; 37,903.0] pg/mL) in breast cancer survivors did not differ significantly from the level of this biomarker in healthy volunteers (29,281.6 [21,786.4; 35,728.2] pg/mL) with p = 0.33. This evidence concerns the gene BDNF and breast cancer.