Introduction: The objective of this study was to investigate the effects of some clinical and pathological features of prolactinomas on tumour behaviour. Material and methods: The study included 113 patients with prolactinoma (27 male, 86 female), with a mean age at diagnosis of 34.4 ± 10.0 years (40.3 ± 12.6 in males, 32.6 ± 8.3 in females). Patients were grouped as invasive or non-invasive according to radiological imaging findings. Ki-67 levels were evaluated if possible. Results: The mean adenoma size (longest dimension) was 38.6 ± 21.6 mm and 10.8 ± 9.4 mm in male and female patients. Pre-treatment serum levels of prolactin were defined as mean 1,926 ± 6,662 ng/mL in all, 124.8 ± 63.4 and 4,675 ± 10,049 ng/mL in the noninvasive and invasive groups (p < 0.05). A positive correlation was found between the serum levels of prolactin and tumour size. The rate of patients with Ki-67 ≥ 0.03 was 37.5% and 47.8% in the noninvasive and invasive groups. The reduction rates were 60.8% and 80.4% in tumour sizes and 81.1% and 93.8% in prolactin level in the noninvasive and invasive groups, respectively, (p < 0.05). Conclusions: We found a strong correlation between prolactin levels and invasiveness in male patients compared to females. Ki-67 index was not found to have a place in defining the prognosis. Introduction: The objective of this study was to investigate the effects of some clinical and pathological features of prolactinomas on tumour behaviour. Material and methods: The study included 113 patients with prolactinoma (27 male, 86 female), with a mean age at diagnosis of 34.4 ± 10.0 years (40.3 ± 12.6 in males, 32.6 ± 8.3 in females). Patients were grouped as invasive or non-invasive according to radiological imaging findings. Ki-67 levels were evaluated if possible. Results: The mean adenoma size (longest dimension) was 38.6 ± 21.6 mm and 10.8 ± 9.4 mm in male and female patients. Pre-treatment serum levels of prolactin were defined as mean 1,926 ± 6,662 ng/mL in all, 124.8 ± 63.4 and 4,675 ± 10,049 ng/mL in the noninvasive and invasive groups (p < 0.05). A positive correlation was found between the serum levels of prolactin and tumour size. The rate of patients with Ki-67 ≥ 0.03 was 37.5% and 47.8% in the noninvasive and invasive groups. The reduction rates were 60.8% and 80.4% in tumour sizes and 81.1% and 93.8% in prolactin level in the noninvasive and invasive groups, respectively, (p < 0.05). Conclusions: We found a strong correlation between prolactin levels and invasiveness in male patients compared to females. Ki-67 index was not found to have a place in defining the prognosis.

Pituitary tumors usually originate as benign sporadic adenomas and develop into invasive and aggressive tumors such as prolactinomas, which are common functioning pituitary adenomas. The aim of the present study was to examine the association between the tumor behavior in prolactinomas and the p16(CDKN2A) gene polymorphism occurring at the 3'?untranslated region of exon 3 (C540G). A total of 104 patients with prolactinoma were included and assigned to two groups based on invasive vs. non?invasive tumor behavior. Ki67 indices were recorded according to histopathology results. Genotypic analysis of the p16(CDKN2A) C540G polymorphism was carried out using a modified polymerase chain reaction?restriction fragment length polymorphism assay. The corresponding frequencies for CC, CG and GG genotypes in non?invasive vs. invasive tumors were 61.5, 30.8, 7.7 and 64.1, 28.2, 7.7%, respectively (not significant). The observed CG genotype frequency was higher compared with previous studies. In addition, the patients with giant adenomas or a high Ki67 index had a higher frequency of the CG genotype as compared with the other subgroups, although the differences were not significant (46.2 and 42.9%, respectively). In conclusion, a higher frequency of the C540G CG genotype of the CDKN2A gene was found among patients with prolactinoma in comparison with previous studies. These frequencies were also higher in the subgroups with elevated Ki67 or giant adenomas. Further studies are required to improve the definition of the role of the CG genotype in the development and progression of tumors in prolactinomas.