In the training set, the median serum CPT1A level in breast cancer patients was 40.22 ± 35.12 ng/mL, which was significantly higher than that of patients with benign breast disease (18.44 ± 14.61 ng/mL; p < 0.0001) or healthy controls (14.37 ± 14.56 ng/mL; Fig. 2a, p < 0.0001). Here, CPT1A is linked to breast fibrocystic disease.