Introduction: Pituitary adenomas are benign neoplasms which grow slowly, but that can recur even after apparent radical resection. Until now, markers predicting regrowth and invasiveness have not been completely characterized.
Design: We investigated cell proliferation and apoptosis parameters in 20 radically resected pituitary macroadenomas (six GH, two PRL, two ACTH, one FSH and nine non-secreting), in order to predict recurrence risk. Tumour regrowth was demonstrated by MRI in a 5-year follow-up. Proliferative activity and DNA ploidy were analyzed by flow cytometry (FCM) performed on fresh surgical specimens. Immunohistochemical expression of proliferative index MIB-1 and of anti-apoptotic protein Bcl-2 was analyzed on paraffin-embedded specimens.
Results: Six adenomas recurred after surgery, regardless of hormonal hypersecretion. Pre-surgical tumour size was not significantly higher in recurrent than in non-recurrent adenomas (P=0.08). Pre-surgical MRI demonstrated cavernous sinus (CS) invasiveness in all recurred tumours and in 6 non recurred ones (P=0.042, by Fishers exact test). FCM showed aneuploid DNA content in 5/20 adenomas, one of which recurred. Cell percentages in S (%SPF) and G2+M (%G2-M) phase and proliferative index (PI=%SPF+%G2-M) were significantly higher in aneuploid than in diploid adenomas (P<0.05), but tumour recurrence was independent of all FCM parameters. MIB-1 expression and mean percentage of MIB-1+ve cells were higher in recurrent than in non-recurrent tumours, although not significantly (P=0.094 and P=0.061, respectively). Bcl-2 expression was detected in 12/15 pituitary adenomas, involving 63±35% of tumor cells, regardless of tumour recurrence.
Conclusion: In this group of radically resected pituitary macroadenomas, neuroradiological finding of CS invasiveness, but neither FCM parameters nor MIB-1 and Bcl-2 expressions, is useful for predicting tumour recurrence.
30 Apr - 04 May 2011
European Society of Endocrinology