Endocrine Abstracts

Majority of prolactinomas consists of the small microadenomas that can be treated with dopamine agonists, but they can present different biological behavior features and not infrequently seen as macroadenomas or in giant adenoma size. There are different results on finding of studies which investigate the relationship between high levels of cell proliferation indicators with tumor behavior in pituitary adenomas. In this study, Ki 67 index to investigate the relationship between tumor behavior and treatment response rates.

Thirty-one patients with the diagnosis of operated prolactinoma were included the study. The patients were divided into two groups as having non-invasive tumor and invasive tumor. The patients with a Ki67 index ≥3/100 were considered as having a tumor with high proliferative property. The patients cured with surgical treatment those had a normal level of prolactin after the surgery or with the primary medical therapy with at least 50% reduction in the tumor diameter and without worsening of these responses after cessations of the medical therapy were grouped as the patients with good responses.

High proliferation values were found in 14 (45.2%) patients, while Ki67 indices <0.03 were defined in 17 (54.8%) patients. Rate of the patients with Ki67 ≥0.03 was 37.5% in the noninvasive group and 47.8% in the invasive group. The difference between two groups was not found statistically significant. Reduction in tumor size and prolactin level were found respectively 75.19 and 90.96% in low Ki67 group while 86.36 and 88.16% in high Ki67 group (P=0.561, P: 0.922). When the responses to the treatment were evaluated in terms of the Ki67 cell proliferation indices, no statistically different was found between the groups with high and low indices in terms of the change in tumor size or prolactin level.

Mean levels of Ki 67 index were determined quite close in non-invasive and invasive prolactinomas. Three patients (37.5%) in Invasive group and 11 patients (47.8%) in non-invasive group were high level of Ki67 index. In addition, Ki67 index does not change the results of treatment. According to these results, Ki67 index has not prognostic indicator in patients with prolactinoma.

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.