Black Patients with Pituitary Tumors Have Greater Ki67 Levels, Which Is Independently Associated with Increased Tumor Volume

Introduction: Pituitary adenomas represent the most common tumor found in the sella turcica. They vary greatly in their composition, as they can be nonfunctional and exhibit symptoms of mass effect, or they can secrete hormones in addition to their mass effect. Ki67, a marker of cellular proliferation, has been studied extensively in pituitary neoplasia. Some studies show correlation between Ki67 levels and tumor subtype, but those findings are non-uniform. Similarly, there are inconsistent findings in the association between Ki67 levels and degree of invasion. Finally, it is still unclear from existing data whether Ki67 levels are in any way correlated to frequency of tumor recurrence.

Objective: In this single-center study, we aimed to determine if Ki67 levels were correlated with tumor volumes and recurrence, and assessed if there was a racial component in differences in Ki67 levels.

Methods: We conducted a retrospective chart review of patients treated for pituitary adenoma between 2017 and 2023 at single academic tertiary care center. A total of 139 patients were included in this study. By race, 72 (52%) patients were Black, and 67 (48%) patients were non-Black, which included White, Asian, and other/declined to respond. Tumor volume was calculated using the traditional formula: (AP × CC × TR)/2, where AP, CC, and TR refer to the three dimensions of the tumor in centimeters. With regards to Ki67 levels, patients were categorized as either having low (0–1%) levels or intermediate (>1 to ≤ 3%) levels.

Results: Our analysis showed that those patients with intermediate Ki67 levels had greater tumor volumes in cubic centimeters than those with low Ki67 levels (20.2 [95% CI (12.4, 28.1); n = 23] vs. 14.1 [95% CI (7.5, 20.8); n = 44]; p = 0.049*). However, using Fisher’s exact test to analyze differences in rates of recurrence compared with expected values, there was no difference in rates of recurrence between those with low Ki67 levels and intermediate Ki67 levels (25.0 vs 36.7%; p = 0.24 [n = 102]). Additionally, Black patients were more likely to have intermediate than low Ki67 levels than non-Black patients (42.6% versus 19.6%; p = 0.01* [n = 110]. However, Black patients did not have a significantly larger tumor volume in cubic centimeters than non-Black patients (7.7 [95% CI (4.6, 10.8); n = 53] vs. 8.9 [95% CI (5.8, 12.0); n = 36]; p = 0.43).

Conclusion: In our study, we aimed to add to existing data on trends regarding Ki67 levels, pituitary tumor volumes, and rates of tumor recurrence. We found that those with intermediate Ki67 levels had greater tumor volumes but similar rates of recurrence compared with those with low Ki67 levels. Additionally, we discovered Black patients, also, were more likely to have intermediate Ki67 levels versus low levels. However, this was not associated with increased tumor volume. Other factors need to be assessed to explain why this cohort of patients has greater tumor volumes.

 

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
07 February 2025