Relevance of Ki-67 and prognostic factors for recurrence/progression of gonadotropic adenomas after first surgery

Objective: Gonadotropin-secreting pituitary adenomas carry a high risk of local recurrence or progression (R/P) of remnant tumor after first surgery. The clinical characteristics and the long-term outcome of these silent adenomas, which show no signs of endocrine hyperfunction, differ from those of other types of pituitary adenomas. However, to date, no study has focused specifically on gonadotropic adenomas. Materials and methods: To identify prognostic factors of R/P of remnants, we studied the postoperative outcome of 32 gonadotropic pituitary adenomas, defined on immunohistochemical staining, according to their clinical and radiological characteristics as well as the Ki-67 labeling index (LI). Results: The Ki-67 LI failed to provide independent information for the identification of patients at risk of progression of remnants or recurrence. Multivariate survival analysis (Cox regression) showed that neither invasiveness nor remnant tumors nor hyposomatotropism influenced tumor recurrence. The strongest predicting factors of R/P were the antero-posterior (AP) diameter in the sagittal plane (P=0.014), and the age of the patient at surgery (P=0.047), with younger patients being at greater risk. Hazard ratios were 2.11 for each 5 mm increase in AP diameter and 0.57 for every 10 years of age. Conclusion: The two simple clinical criteria revealed by our study, the AP diameter of the tumor and the age of the patient, should be helpful in planning clinical management and radiological monitoring after first surgery of gonadotropic adenomas, while awaiting the identification of other pathological parameters.