Background: Node involvement, negative estrogen receptor (ER) and HER2 expression are the main negative prognostic factors for breast cancer. Prolactin (PRL) is involved in the control of breast cancer growth and differentiation. Surgery-induced hyperprolactinemia seems to be a positive prognostic factor for operable breast cancer, whereas high PRL levels may predict a poor prognosis in women with metastatic breast cancer. In this study, we evaluated the relation between HER2 expression and PRL blood concentrations in women with metastatic breast cancer women and those whit operable breast cancer patients prior to before and 7 days after surgery.
Patients and methods: The study included 50 women with breast cancer, 22 of whom had metastatic disease. HER 2 expression and serum levels of PRL were evaluated by fluorescence in situ hybridization (FISH) method and immunoradiometric assay (IRMA) method, respectively.
Results: HER2 expression occurred in 11/28 operable cases and in 8/22 metastatic cases. The percentage of surgery-induced hyperprolactinemia was significantly higher in HER2-negative patients than in those with its expression. Moreover, HER2-positive metastatic cases showed significantly higher mean serum PRL levels than in the negative group.
Conclusion: These preliminary results show that metastatic cancer-related hyperprolactinemia and lack of surgery-induced hyperprolactinemia are statistically more frequent in HER2-positive patients, thus suggesting a link between PRL endogenous secretion and HER2 expression in breast cancer.