Ki-67 antigen expression in non-functioning pituitary adenomas is correlated to growth velocity but not to invasiveness

Object. The cell cycle—dependent nuclear antigen Ki-67 is related to growth potential in a variety of tumors. Elevated expression of Ki-67 was previously shown in recurrent pituitary adenomas; however, it has remained unclear whether this expression is related to the growth velocity or invasive behavior of these tumors. The aim of this study was to determine the correlation of Ki-67 antigen expression, growth velocity, and invasiveness in nonfunctioning pituitary adenomas. Methods. Between April 1998 and April 2002, 23 patients with nonfunctioning pituitary adenomas who had participated in an observation period in which multiple computerized tomography and magnetic resonance imaging studies had been performed were surgically treated in our department. Tumor volumes were assessed using a stereological method based on the Cavalieri principle. The growth rate was calculated for each patient. Expression of Ki-67 antigen was examined using the monoclonal antibody MIB-1. The assessed growth velocity of the adenomas was best described by a linear growth model. The correlation between Ki-67 expression and growth rate was highly significant. Rapidly growing adenomas (>0.07% daily increase in size) were found to have a Ki-67 labeling index (LI) exceeding 1.5%, whereas all five adenomas with a very slow growth rate (< 0.02% daily increase in size) had a Ki-67 LI lower than 1.5%. No correlation was found between the growth rate and the invasive character of the adenomas. Conclusions. Expression of Ki-67 antigen is significantly correlated to the growth velocity of pituitary adenomas. Invasive behavior is a feature independent of proliferative activity. The extent of Ki-67 expression is helpful for clinical decision making and routine assessment of Ki-67 is recommended during the histopathological workup of pituitary adenomas.

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MCM7 as a marker of postsurgical progression in non-functioning pituitary adenomas

Acta Endocrinologica ◽

10.1530/eje-20-1086 ◽

2021 ◽

Author(s):

Tobias Hallén ◽

Daniel S Olsson ◽

Casper Hammarstrand ◽

Charlotte Örndal ◽

Angelica Engvall ◽

...

Keyword(s):

Cohort Study ◽

Mitotic Index ◽

Pituitary Adenomas ◽

Tumour Progression ◽

Receptor Expression ◽

Residual Tumour ◽

Operating Characteristics ◽

Stable Group ◽

Ki 67 ◽

Non Functioning Pituitary Adenomas

Objective: Current markers predicting tumour progression of pituitary adenomas after surgery are insufficient. Our objective was to investigate if minichromosome maintenance protein 7 (MCM7) expression predicts tumour progression in non-functioning pituitary adenomas (NFPAs). Methods: In a cohort study of surgically treated NFPAs, two groups with distinctly different behaviour of a residual tumour were selected: one group requiring reintervention due to tumour progression (reintervention group, n=57) and one with residual tumours without progression (radiologically stable group, n=40). MCM7, Ki-67, estrogen receptor-⍺ expression, mitotic index and tumour subtype was assessed by immunohistochemistry and their association with tumour progression requiring reintervention was analysed. Results: Median (IQR) MCM7 expression was 7.4% (2.4–15.2) in the reintervention group compared with 2.0% (0.6–5.3) in the radiologically stable group (P<0.0001). Cox regression analysis showed an association between high (>13%) MCM7 expression and reintervention (HR 3.1; 95%CI:1.7-5.4; P=0.00012). The probability for reintervention within 6 years for patients with high MCM7 was 93%. Ki-67 expression >3% (P=0.00062), age ≤55 years (P=0.00034) and mitotic index ≥1 (P=0.024) were also associated with reintervention. Using a receiver operating characteristics curve, a predictive model for reintervention with all the above predictors yielded an area under the curve of 82%. All eight patients with both high MCM7 and high Ki-67 needed reintervention. Conclusion: This cohort study shows that expression of MCM7 is a predictor for clinically significant postoperative tumour progression. Together with age, Ki-67 and mitotic index, MCM7 might be of added value as a predictive marker when managing patients with NFPA after surgery.

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