Clinicopathological study of prognostic factors in patients with pituitary adenomas and Ki-67 labeling index of more than 3%

Background: Pituitary adenoma is generally indolent, but an aggressive subtype including atypical adenoma has uncertain prognosis, and an unclear relationship between prognosis and morphology. Aim: To investigate the prognostic factors of adenomas with Ki-67 labeling index of more than 3%. Subjects and methods: Patients with surgically treated pituitary adenomas with Ki-67 labeling index of more than 3% were retrospectively identified as 13 males and 20 females aged from 15 to 73 yr (mean 47.2 yr) among 527 patients with pituitary adenoma treated at the Department of Neurosurgery, Tohoku University and Department of Neurosurgery, Kohnan Hospital between January 2001 and December 2007. Results: The tumors included 12 cases of gross totally removed pituitary adenomas, and 21 non-totally removed adenomas. Statistical analysis found significant differences in recurrence between gross total and non-total removal (log-rank test, p<0.001), and giant adenomas had higher risk of recurrence or re-growth (log-rank test, p<0.01); 71.4% of re-growth was detected within 12 months if the patients had tumor remnants after the operation. Both immunohistochemical types of tumor and invasion of the surrounding tissue had no statistical correlation with tumor regrowth, and high Ki-67 and p53 labeling index had no relationship with duration of stable disease among these patients independently. Conclusions: Gross total removal is the most important prognostic factor in patients with adenoma with Ki-67 labeling index of more than 3%. In contrast, giant adenoma carries higher risk of recurrence and/or re-growth. If gross total removal is not achieved immediate adjuvant therapy should be performed.