In the serum of HER2+ BC women, the antioxidant capacity is the lowest and impacts the absorbance in wavenumbers 3874 cm−1 (β = −0.038; p < 0.001), 3876 cm−1 (β = −0.059; p < 0.001) and 3878 cm−1 (β = −0.066; p < 0.001). This evidence concerns the gene ERBB2 and breast cancer.