Prolactin levels are correlated with tumor size and invasiveness in prolactinomas
S Cander1,2, E Erturk2, O Oz Gul2, O Unal2, C Ersoy2, E Tuncel2 & S Imamoglu2
Prolactinomas are more common tumors by 60% among the hypophysis adenomas. These are often benign, but may present differences in terms of tumor size and treatment responses. Aim of this study was investigate the relationship of serum prolactin levels with tumor size and invasiveness in the prolactinomas.
113 patients with the diagnosis of prolactinoma were included to study. Pretreatment plasma levels of prolactin in the time of diagnosis and sella MR imaging findings. According to the sella MR imaging findings during the diagnosis, the tumors were defined as microadenoma (the longest diameter <1 cm), macroadenoma (the longer diameter between 1 and 4 cm), giant adenoma (the longest diameter >4 cm), invasive and non-invasive adenoma.
The mean age at the time of diagnosis was 34.4±10.0 years in 113 patients. The mean age of diagnosis was found as 40.3±12.6 in the male and 32.6±8.3 in the female patients. The mean size of adenoma was found as 17.9±18.1 mm in all the patients, 38.6±21.6 mm in the male and 10.8±9.4 mm in the female patients. Pre-treatment serum levels of prolactin were mean 1926±6662 ng/ml. Positive correlation was defined in the correlation analysis between the pre-treatment serum levels of prolactin and tumor size. The correlation coefficient was found as 0.805 in the correlation analysis applied between log10 values of the prolactin levels (ng/ml) and tumor size (mm) (Figure ). When the case with a serum level of prolactin higher than 3300 ng/ml were examined (n:8), all are seen to fall into the invasive adenoma group. Of patients with a lower serum level of prolactin, 61 were seen to be in the noninvasive and 32 in the invasive group. When the cut-off value was taken as 400 ng/ml, sensitivity was calculated as 70% and specificity as 100%.
These findings show serum levels of prolactin to be an important factor in the definition of tumor behavior. As it is indicated in the previous studies, a strong correlation was found between the prolactin levels and the size and invasiveness of tumors in our study.
Figure 1 Correlation between pretreatment prolactin level and tumor size.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.