SAT-086 - Beyond Immuno Histochemistry: Qrt-PCR-Based Ki-67 Assessment in Pituitary Adenomas

Abstract
Background
Pituitary adenomas are common intracranial neoplasms that may exhibit aggressive behavior, including rapid growth and invasiveness. The Ki-67 labeling index (LI) is widely used to assess tumor proliferation, but interobserver variability in immunohistochemistry (IHC) can limit its reliability. This study evaluates the correlation between Ki-67 expression by IHC and quantitative real-time PCR (qRT-PCR) in pituitary tumors to determine the potential utility of molecular assessment in clinical practice.

Methods
This cross-sectional analytical study was conducted at Gandhi Medical College and Hospital between August 2022 and July 2024. Twenty adult patients undergoing surgery for pituitary adenomas were enrolled. Tumor tissues were assessed for Ki-67 expression using IHC and qRT-PCR. Radiological assessment of invasiveness was done using KNOSP and Hardy classification on MRI. Statistical analysis included Fisher’s exact test and Mann-Whitney U test, with a significance threshold of p ≤ 0.05.

Results
A statistically significant correlation was observed between Ki-67 LI by IHC and Ki-67 mRNA expression by qRT-PCR (mean CT values: 22.03 for Ki-67 LI >3%, and 24.62 for Ki-67 LI ≤3%, p = 0.005). However, no significant correlation was found between Ki-67 expression (by either method) and radiological invasiveness based on KNOSP or Hardy classification. The majority of tumors were non-functioning adenomas or acromegaly-related, which may explain the absence of correlation with invasiveness.

Conclusion
Ki-67 mRNA expression assessed by qRT-PCR correlates significantly with IHC findings and offers a more objective and reproducible measure of proliferative activity in pituitary adenomas. qRT-PCR may serve as a complementary or alternative tool to IHC in evaluating tumor aggressiveness, particularly in cases with ambiguous IHC results. Further large-scale, prospective studies are warranted to validate its prognostic utility.

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