Relation of proliferation and apoptosis indexes to the invasiveness of pituitary adenomas

Objective To investigate the proliferation and apoptosis characteristics of pituitary adenoma cells,and to discuss the relative factors of the invasiveness of the tumor and the early diagnosis.Methods Formalin-fixed samples of pituitary adenomas were immunohistochemically stained using Ki-67 monoclonal antibody.To the fresh samples,cell proliferation and apoptosis were analyzed with cytoflowmetry.Results Forty-eight formalin-fixed samples were studied,including 28 cases of invasive adenomas and the remaining 20 non-invasive.Positive stains of Ki-67 were found in 13 cases of invasive adenomas(13/28)and 6 in non-invasive ones(6/20,χ~2=5.486,P=0.019).With Ki-67 positive staining,the diagnosis sensitivity of invasive tumor was46.5%.the positive predictive value was 68.3%.Thirty-three fresh pituitary adenoma samples were studied,including 15 invasive and 18 non-invasive cases.S-phase fraction in invasive tumors was 3.9%-24.2%(average13.0%).while in non-invasive tumors it was 0.8%-12.2%(average 4.8%).Significant ditierence existed between two groups(t=3.745,P=0.001).The diagnosis sensitivity of invasiveness was 40%and the positive predictive value was 100%using the cup-point of>13.0%.The apoptosis cell percentage was 5.1%-27.0%(average 12.5%)in invasive and 3.6%-30.3%(average 16.2%)in non-invasive adenomas(t=1.25,P=0.22).The ratio of S-phase cells to apoptosis cells(S/A)were 1.411 and 0.399 in invasive and non-invssive groups,respectively(t=4.62,P 1.411,the diagnosis sensitivity of invasiveness was 60%and the positive predictive value was 100%.Conclusions Between invasive and non-invasive pituitary adenomas.the proportions of proliferative cells and apoptosis cells seem to be different.High proliferation denotes poor sensitivity in diagnosing invasiveness,and imbalance between proliferation and apoptosis may be more sensitive and specific in regarding invasiveness. Key words: Pituitary adenomas; Invasiveness; Proliferation; Apoptosis