Immunohistochemical expression and prognostic significance of the biological markers bcl-2, p53, mdm-2 and ki-67 in early stages of invasive cervical carcinomas

Abstract

Objectives: The objectives of this study were the evaluation of the immunohistochemical expression of apoptosis regulating proteins (bcl-2, mdm-2 and p53 protein) in correlation with proliferation (Ki-67), human papillomavirus (HPV) infection and other histopathological and clinical parameters in early stage cervical carcinomas and estimation of their prognostic significance. Methods: The subject of this study was a series of 83 surgically treated patients with cervical carcinoma confined to the uterine cervix, who subsequently received complete radiotherapy. The presence of HPV DNA in the neoplasm was determined by the conventional method of in situ hybridization (ISH) and catalyzed reporter deposition signal amplification ISH using mixed biotinylated probes to identify types 6/11, 16/18 and 31/33 or 31/33/51. The immunohistochemical expression of the biological markers was semiquantitatively evaluated as the percentage of immunostained cells in the three compartments of the neoplasm: the surface, the middle layer and the invasive front. Results: 73 patients had a tumor confined to the uterine cervix less than 4 cm in diameter (pT1b1) and the other 10 had larger neoplasms that belong to the pT1b2 category. Regional lymph node involvement was found in 20 (24%) of the patients. During the clinical follow-up (mean, 120.7, range 4.4-181 months) a relapse was diagnosed in 9 (10.8%) patients, 6 of which (7.2%) died of the disease. The expected 5-, 10- and 15- year overall survival was 94.4%, 92.7% and 92.7%, and disease-free survival was 92.7%, 90.8% and 86.6%, respectively. The results of the univariate analysis indicate that significant predictive indicators for recurrence are: lymphonodal status, maximal tumor diameter, depth of stromal invasion, histological type, HPV DNA presence and type, and the immunohistochemical expression of bcl-2, mdm-2 and Ki-67 in the invasive front of the neoplasm. In the multivariate analysis, histological type, HPV DNA presence and the expression of Ki-67 in the invasive front have been selected as the most significant independent prognostic parameters (P=0.0024). The value of the prognostic index (PI), calculated using the Cox regression model, provided the basis on which the patients were classified into two distinct risk groups with significantly different disease-free survival period (P=0.0009). Conclusions: The results indicate that the invasive front of the neoplasms proved to be the most important area for the evaluation of immunohistochemical expression of biological markers. The prognostic index as an indicator of the patient’s place in the prognostic spectrum enables the identification of the risk group of patients in whom, due to a higher risk of relapse, better results are to be expected with the application of more aggressive therapy.