High plasma prolactin is associated with PRL-R and predicts poor prognosis in Chinese postmenopausal women with breast cancer.

BACKGROUND

Prolactin (PRL) plays an important role in mammary epithelial cell development and lactation. Increased levels of PRL are observed in human breast cancer, but the underlying mechanism and prognostic significance of PRL are still controversial. In this study, we sought to determine the significance of PRL in Chinese postmenopausal women with breast cancer.

METHODS

Plasma PRL levels in 326 healthy individuals and 333 postmenopausal breast cancer patients were analyzed. Immunohistochemical staining of cytoplasmic prolactin receptor (PRL-R) was performed. Moreover, the relationships between plasma PRL and clinicopathological parameters as well as survival in breast cancer patients were evaluated.

RESULTS

We found that high plasma levels of PRL was more common in breast cancer patients than in healthy individuals. We also observed that high level of PRL was associated with adverse prognostic factors, such as larger tumor size, more lymph node metastasis, advanced tumor stage, negative estrogen receptor (ER) expression, and negative progesterone receptor (PR) expression of breast cancer. Kaplan-Meier analysis showed that high plasma level of PRL correlated with poor disease-free and overall survival, while Cox regression models demonstrated that high plasma level of PRL was an independent prognostic marker for disease-free survival. The rate of PRL-R positivity among those with high plasma PRL was significantly higher than that of patients with low PRL (P < 0.05).

CONCLUSION

The plasma PRL level and PRL-R expression in tumor tissue may be prognostic for Chinese postmenopausal women with breast cancer. The inhibition of PRL and PRL-R signaling is a potential therapeutic approach for endocrine therapy in breast cancer.