PRL and Osteopenia: After normal distribution tests and intergroup comparison analyses were performed, the following screening indicators with significant differences between the osteopenia and normal bone mass groups were obtained: duration of breast cancer (p = 0.001), duration of aromatase inhibitor treatment (p = 0.002), major osteoporotic fracture index (p < 0.001), hip fracture index (p < 0.001), prolactin (PRL) (p = 0.012), and osteocalcin (OC) (p = 0.025).