Hyperprolactinemia is an indicator of progressive disease and poor prognosis in advanced breast cancer.

In a long-term follow-up study, prolactin levels were measured in 149 patients with advanced metastatic breast cancer. Control groups included 221 patients with primary operable breast cancer and 150 women with benign breast disease. Hyperprolactinemia (greater than 1,000 mIU/I; HYPRL) occurs in 44% of patients with metastatic breast cancer in the course of the disease (p less than 0.001 compared to patients with non-metastatic disease). HYPRL is associated with progressive breast cancer in 88% of cases. In patients experiencing several episodes of disease remission and relapse, incidence of HYPRL increases with each relapse. Prolactin blood levels return to normal if hyperprolactinemic patients experience remission after chemotherapy. Patients expressing HYPRL have a shorter survival time after mastectomy when compared to patients who never developed HYPRL (154/89 months, p = 0.01). It is concluded that HYPRL is of prognostic significance and a reliable indicator of progressive disease in advanced metastatic breast cancer.