PURPOSE: Given prolactin's (PRL) multifaceted roles in mammary tissue, an association between hyperprolactinemia and breast cancer has been hypothesized. Despite previous studies not identifying this risk, we aimed to investigate whether a connection exists. METHODS: This retrospective cohort study compared breast cancer incidence in patients with dopamine agonist (DA)-treated hyperprolactinemia versus matched controls in a 1:5 ratio. The primary outcome was a breast cancer diagnosis following hyperprolactinemia diagnosis. RESULTS: The cohort consisted of 1484 female patients with DA-treated hyperprolactinemia matched to 7418 female controls (mean age at diagnosis 32.70 ± 11.12 years
BMI 25.60 ± 5.84 kg/m CONCLUSION: Overall, patients with DA-treated hyperprolactinemia did not show an increased risk for breast cancer compared to controls. However, the risk was significantly higher among those whose PRL levels were <
5×ULN, had advanced age of diagnosis, or prolonged time to PRL normalization.