A critical reappraisal of MIB-1 labelling index significance in a large series of pituitary tumours: secreting versus non-secreting adenomas.

Abstract

Pituitary tumours are usually benign neoplasia, but may have a locally aggressive or malignant evolution. This study aimed to identify factors which mostly influence their proliferative activity, in order to clarify its value for clinical and research purposes. The proliferative index was determined in a prospective series of 132 pituitary tumours as the percentage of monoclonal antibody MIB-1-immunopositive cells and referred to as the MIB-1 labelling index (LI). Its distribution was analysed according to both univariate and multivariate models. A life-threatening pituitary tumour is presented separately. The mean LI was 1.24 ± 1.59%, with significant differences between clinically secreting (CS) and clinically non-secreting (CNS) adenomas. In CS adenomas (n = 65), LI was highly variable and markedly influenced by pre-operative pharmacological treatment (0.80 ± 1.03 vs 2.06 ± 2.39% in treated vs untreated cases, P = 0.009); it decreased with patient's age (P = 0.025, r = 0.28) and increased with tumour volume and invasiveness. The influence of pre-operative treatment and macroscopic features on LI in this group was confirmed by multivariate analysis. In CNS adenomas (n = 67), LI distribution was less variable than in CS adenomas (P < 0.0001), it was age-independent and correlations with tumour volume, invasiveness or recurrence did not reach significance. In a rapidly growing parasellar tumour, the mean LI was 24% at first surgery and exceeded 50% at second surgery performed 4 months later. LI should be interpreted according to hormone secretion and pre-operative treatment. Unusually high LI values deserve particular attention.

Ki-67 Expression for Predicting Progression of Postoperative Residual Pituitary Adenomas: Correlations With Clinical Variables

“…A higher proportion of nonfunctioning adenomas was found in the group with progression, possibly because nonfunctioning adenomas were all macroadenomas, many with suprasellar extensions. 8) In contrast, mean MIB-1 labeling index values were significantly higher in clinically secreting pituitary adenomas without preoperative treatment compared with clinically non-secreting adenomas, 13) as many other authors reported. 28,30) The effect of pre-surgical medical treatment might have caused the variability in these findings.…”

“…13,29) In addition, mean patient age was significantly younger in the J. Matsuyama progression group compared with the non progression group. Both of our findings regarding age suggest slower growth rate of elderly patients.…”

“…20) Some studies also demonstrated a correlation between MIB-1 labeling index and re-growth or recurrence, 9,14,30,32) but other studies found no such correlations. 5,13,24,27) These discrepancies and differences between estimates of the threshold MIB-1 labeling index may be attributable to variations in the definition of recurrence or progression. 26) Another possible source of differences or discrepancies is the method used to count the labeled cells.…”

“…8,18) Various attempts have been made to establish markers that correlate with the clinical behavior of pituitary adenomas, such as invasion, recurrence, or malignancy. 1,2,5,[7][8][9][10][12][13][14][15]17,[19][20][21][22][23][24][27][28][29][30][31][32][33] Among the available methods of growth fraction determination, Ki-67 is a reliable marker for growth fraction determination of various specific cell cycle antigens. 1,12,32) Ki-67 is a protein which reacts with a …”

Expression of galectin-3 correlates with apoptosis in pituitary adenoma cells

“…High proliferative activity is the basis of invasive growth for pituitary adenoma. Many researches have revealed that the invasiveness of pituitary adenoma is affected by adenoma cell proliferative activity [5,6] , but the effect of cell apoptotic activity on invasiveness remains unknown. In this study, the expressions of Gal-3, Bcl-2 and Bax were measured in human pituitary adenoma to explore the interrelation and the effect of them to the invasiveness of pituitary adenomas.…”