Expression and clinical significance of Ki-67, oestrogen and progesterone receptors in acoustic neuroma

Objective: The objective was to assess the presence of Ki-67, and oestrogen and progesterone hormone receptors as well as their clinical correlates in acoustic neuroma. Methods: Medical records of 59 patients who were operated on for acoustic neuroma between 1995 and 2003 were evaluated retrospectively. Formaldehyde-fixed paraffin-embedded archival acoustic neuroma specimens of the patients were used for immunohistochemical assessments of oestrogen and progesterone hormone receptors, and Ki-67 proliferative marker. Results: Tumour sizes were small (< 19 mm), medium (20-39 mm) and large (> 40 mm) in 21, 35 and 3 patients, respectively. On immunohistochemistry, all samples were (+) for progesterone receptor and (-) for oestrogen receptor staining. Ki-67 staining was encountered in 34 of 59 (57.6 per cent) patients, and Ki-67 values ranged from 0 per cent to 10.9 per cent (mean 1.36 per cent). There was no correlation between Ki-67, gender, tumour size and symptoms of the patients (p > 0.05). Conclusion: Oestrogen is not an important hormone in acoustic neuroma due to the absence of oestrogen receptor expression in the tissue samples. Since the progesterone receptor is expressed in all acoustic neuroma samples, further studies are necessary to find out about the inhibitory effect of antiprogesterone treatment on acoustic neuroma growth, which may be important particularly in elderly people or high-risk patients. Although Ki-67 is expressed in the majority of acoustic neuromas, it is not an important marker in clinical practice due to a lack of any correlation with the clinical parameters.