Nucleolar organiser regions (AgNORS) in anal intraepithelial neoplasia and invasive anal

Aim: To evaluate the usefulness of counting nucleolar organiser region associated proteins (AgNORs) in the management of anal squamous neoplasia. Method: Using a silver staining technique for NOR associated proteins, 32 routinely processed paraffin wax embedded sections of anal epithelium were assessed. These consisted of normal anal epithelium (n = 9), anal intraepithelial neoplasia (AIN) grades I (n = 5), and III (n = 13), and invasive squamous neoplasia of the anus (n = 5). Results: The median AgNOR counts for every 100 cells are as follows: normal anal epithelium 2-15 (95% CI 1.89-3.94); AIN I 3-21 (95% CI 2-89-7-14); AIN III 4-32 (95% CI 4-00-8-10); and invasive squamous cell carcinoma of the anus 5 51 (95% CI 2.48-10.62). There were significant differences between AgNOR counts in anal cancer and normal epithelium (p < 0 05; Mann-Whitney U test)), AIN III and normal anal epithelium (p < 0.005), and AIN III and AIN I (p < 0.05). No significant differences were observed between AIN I and normal anal epithelium, anal cancer and AIN I, and anal cancer and AIN III. There was a considerable degree of overlap among the different groups. Conclusions: Despite the strong association between AgNOR values and degree of dysplasia, the variability within pathological grade may preclude the adoption of this technique on its own as a prognostic indicator. It may, however, be useful in conjunction with other markers of neoplastic growth such as c-myc oncogene amplification or overexpression as a marker of disease progression in AIN and invasive anal squamous cell cancer. Department of Surgery, Clinical Sciences Centre, Northern General Hospital, Sheffield S5 7AU