Importance of serum prolactin determination in metastatic breast cancer patients

To correlate prolactin concentrations in the sera of patients with metastatic breast cancer with time interval to appearance of metastases, their location, and size.

The prospective study included 46 female patients with histologically confirmed diagnosis of breast cancer. The patients were recruited from the Health Center outpatient clinic and University Hospital Center day-care hospital in Banja Luka, Bosnia and Herzegovina, from January to August 1988. The follow up lasted 5 years. Serum concentrations of prolactin were measured in all patients before (baseline levels) and after the therapy at regular time intervals during the observation period. Their prolactin concentrations were compared with prolactin concentrations in 40 healthy women and 33 female patients with other types of cancer, who served as control groups. Time interval to metastases development, their size, and location were determined in breast cancer patients and compared with those in patients with other types of cancer.

The baseline serum concentrations of prolactin were higher in breast cancer patients than in healthy women (610 vs 442 mU/L; p=0.04; Mann-Whitney test), and in patients with other locations of cancers (662 vs 481 mU/L, respectively; p=0.02; Mann Whitney test). Metastases developed in all hyperprolactinemic patients, whereas a third of normoprolactinemic were free of metastases. The average time interval before the occurrence of metastases in patients with very high serum concentrations of prolactin was significantly shorter than that in patients with very low prolactin concentrations (54.3 vs 6.1 months; p<0.001; Mann Whitney test). In hyperprolactinemic patients with metastatic breast cancer, there was a significant correlation between the serum concentration of prolactin before treatment and the time to metastases (r= -0,47; p=0.03) and the size of metastases (r=0,64; p=0.001).

Hyperprolactinemia could be an indicator of disease progression and poor prognosis in patients with metastatic breast cancer.