Clinical Significance of Ki-67 Labeling Index in Pituitary Macroadenoma

Abstract

The aim of our study was to investigate the correlation of the proliferative activity of pituitary neoplasms with clinical characteristics and recurrences. Tumor specimens were obtained from 44 consecutive patients with pituitary macroadenomas who underwent surgery between July 1998 and August 2003. Specimens were immediately fixed in 10% buffered formalin and then embedded in paraffin. The Ki-67 antigen was assessed by immumohistochemical analysis using the monoclonal antibody. We investigated the correlation of the Ki-67 labeling index with the following clinical and radiological characteristics: sex, age, presence or absence visual field defect, tumor classification, maximal tumor diameter, Hardy's classification, type of tumor, invasiveness, and recurrence. Our study suggests that the clinical characteristics such as visual field defect and recurrence are correlated with the high Ki-67 labeling index. No statistical differences were observed in the Ki-67 labeling index in relation to the following characteristics: sex, age, tumor classification, maximal tumor diameter, Hardy's classification, type of tumor, and invasiveness into the sphenoid sinus or cavernous sinus.

Apparent diffusion coefficient and pituitary macroadenomas: pre-operative assessment of tumor atypia

“…Invasive pituitary adenomas that exhibit relatively higher mitotic activity, MIB-1 labeling index of [ 3 %, and excessive p53 immuno-reactivity are classified as atypical adenomas by the World Health Organization [6,9]. Furthermore, these atypical adenomas have been associated with higher risk of recurrence or lack of therapeutic response [9,10,13]. Our study found a statistically significant difference in the proliferation marker MIB-1 as well as the ADC values in invasive pituitary adenomas as compared to noninvasive pituitary adenomas.…”

“…Markers of cell proliferation, such as the immunohistochemical detection of Ki-67 antigen have been suggested as biomarkers for aggressive behavior in atypical pituitary adenomas [3,9,10]. Ki-67 is a nuclear antigen expressed in proliferating cells identified by monoclonal antibody MIB-1 [10].…”

“…Ki-67 is a nuclear antigen expressed in proliferating cells identified by monoclonal antibody MIB-1 [10]. The role of MIB-1 as a proliferation marker is well established in the pathology literature, and numerous studies have investigated the potential of MIB-1 labeling index in identifying more aggressive tumors, including meningiomas and gliomas [11,12].…”

“…The role of MIB-1 as a proliferation marker is well established in the pathology literature, and numerous studies have investigated the potential of MIB-1 labeling index in identifying more aggressive tumors, including meningiomas and gliomas [11,12]. Although there is no well established threshold for proliferative markers such as MIB-1 immunohistochemistry, prior studies demonstrated higher MIB-1 indices in recurrent adenomas, suggesting a potential for MIB-1 labeling index as a biomarker for more aggressive, atypical adenomas [10,13].…”

MKI67 (marker of proliferation Ki-67)

“…The MKI67 expression is correlated with neoplasm recurrence and visual field defect (Paek et al, 2005). Additionally, it is believed to be an independent predictor of pituitary adenomas' progression after surgery (Gejman et al, 2008).…”