The Relationship of Circulating Prolactin Levels to The Size of Primary Tumor in Breast Cancer Patients

Rationale: data about the role of prolactin (PRL) in breast cancer patients are controversial. This hormone might potentially play an important role in breast cancer initiation and development in rodents, as well as, at least partly, in humans. The aim of this study was to investigate the possible relationship between circulating levels of PRL and parameters of primary tumor in breast cancer patients. The main experimental group consisted of 46 female patients with histologically confirmed diagnosis of breast cancer. There were two control groups: apparently clinically healthy women (40), and female patients with other types and locations of cancer (33). Baseline levels of PRL were determined both in the main and in control groups. Parameters of primary tumor (histological diagnosis, degree of differentiation, location, and size) have been determined. Results were processed by means of nonparametric tests. The circulating levels of PRL before treatment were significantly higher in breast cancer patients in comparison to controls. The average size of the primary tumor in breast cancer patients with hyperprolactinemia before treatment was significantly higher (U=125.5, p<0.01) than in those with normoprolactinemia. The calculated correlation coefficient between PRL and the size of primary tumor in hyperprolactinemic breast cancer patients was statistically significant (r=0.68, p<0.0001). In normoprolactinemic, and in patients with other locations of cancer such a correlation did not exist. Serum levels of PRL are, probably, directly dependable on the size of primary tumor in breast cancer patients, especially in those with hyperprolactinemia, but this is not differentiation dependent phenomenon.