086. Correlations between ki-67 labeling index of nonfunctioning pituitary adenomas with clinical characteristics and follow-up

P. Martini, A. Franzin, M. Losa, F. Mangili, M. R. Terreni, R. Barzaghi, M. Giovanelli

Research output: Contribution to journalArticlepeer-review


Aim of the study: Nonfunctioning pituitary adenomas (NFPA) account for 25% of all pituitary adenomas. The clinical presentation of NFPA is usually secondary to symptoms of mass effect, such as visual disturbances, headache, and impaired pituitary function. So, almost all NFPA are large extrasellar macroadenomas and approximately half of all the patients will have tumor remnants after surgery. Selection of patients available for postoperative radiotherapy would be of considerable help if we could identify the factors that predict the probability of tumor recurrence. We studied the correlation between the growth fraction of NFPA with clinical characteristics and follow-up. Material and method: We determined the percentage of cells positive for the Ki-67 antigen, a nuclear protein of unknown function whose expression is limited to the mitotic phase of the cell cycle in a large group of patients with NFPA. Tumor specimens were obtained from 101 consecutive patients (48 women and 53 men) with NFPA operated in San Raffaele Hospital from 1990 to 1995. The Ki-67 antigen was assessed by immunocytochemistry using the monoclonal antibody MIB-1. MIB-1 immunostaining was performed using the avidin-biotin-peroxidase complex method. The Ki-67 antigen labeling index (Ki-67 LI) was determined by counting a total of at least 1000 neoplastic nuclei. Results: The mean Ki-67 LI in the 101 patients was 2.4% ± 0.3% (from 0% to 23.0%). Sex, maximum tumor diameter, and invasiveness into the cavernous sinus did not affect the Ki-67 LI significantly; whereas age at operation inversely correlated with Ki-67 LI. During follow-up (39.7 ± 2.1 months) 23 patients had tumor recurrence. Invasiveness of the tumor on preoperative MRI was the most important predictor of late tumor recurrence followed by previous pituitary surgery, younger age, and lack of postoperative radiotherapy. The Ki-67 LI had no independent prognostic value. Conclusion: The Ki-67 labeling index does not provide independent information to identify patients with higher risk for tumor recurrence.

Original languageEnglish
Pages (from-to)32-33
Number of pages2
JournalSkull Base
Issue numberSUPPL. 2
Publication statusPublished - 2001

ASJC Scopus subject areas

  • Clinical Neurology


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