Proliferation index of nonfunctioning pituitary adenomas: correlations with clinical characteristics and long-term follow-up results.
OBJECTIVE
The recurrence of nonfunctioning pituitary adenomas (NFPAs) after surgical removal is common. The aim of our study was to investigate and correlate the growth fraction of NFPAs with clinical characteristics and long-term follow-up results.


METHODS
Tumor specimens were obtained from 101 consecutive patients with NFPAs (48 female patients and 53 male patients; mean age, 52.0 +/- 1.5 yr). Specimens were immediately fixed in 10% buffered formalin and then embedded in paraffin. The Ki-67 antigen was assessed by immunocytochemical analysis using the monoclonal antibody MIB-1. The Ki-67 antigen labeling index (LI) was determined by counting a total of at least 1,000 neoplastic nuclei.


RESULTS
The mean Ki-67 LI for the 101 patients was 2.4 +/- 0.3% (range, 0-23.0%). Only age at surgery was inversely correlated with the Ki-67 LI; sex, maximal tumor diameter, and invasiveness into the cavernous sinuses did not significantly affect the Ki-67 LI. The mean follow-up period was 39.7 +/- 2.1 months. During follow-up monitoring, 23 patients experienced tumor recurrence, after a mean period of 28.6 +/- 4.8 months. Invasiveness of the tumor on preoperative magnetic resonance imaging scans was the strongest 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.


CONCLUSIONS
Our study suggests that the clinical characteristics of patients with NFPAs, except for age at surgery, are not correlated with the Ki-67 LI. Moreover, the Ki-67 LI does not seem to provide independent information to identify patients at high risk for tumor recurrence.
Losa
M
M
Department of Neurosurgery, Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele, University of Milan, Italy. losa.marco@hsr.it
Franzin
A
A
Mangili
F
F
Terreni
M R
MR
Barzaghi
R
R
Veglia
F
F
Mortini
P
P
Giovanelli
M
M
D000236:Adenoma / Q000175:diagnosis / Q000276:immunology / Q000473:pathology*; D002455:Cell Division; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D009364:Neoplasm Recurrence, Local; D010911:Pituitary Neoplasms / Q000175:diagnosis / Q000276:immunology / Q000473:pathology*; D011379:Prognosis
D019394:Ki-67 Antigen