[Cytophotometric expression of tumor antigen markers Ki-67 and CD-34 in prostate adenocarcinoma].

OBJECTIVE

To quantify the percentage of immunostaining through the labeling index as well as the optical density of Ki-67 and CD34 in prostate adenocarcinoma and compare the results between markers.

METHODS

Markers Ki-67 and CD34 were studied using immunohistochemistry in 34 cases of prostate adenocarcinoma from radical prostatectomies performed at the Hospital Regional do Gama in Brasilia, Brazil from 2000 through 2005. Those markers were quantified using the SAMBA 4000 software - Automated Scanning Microscopic Analysis System - and the IMMUNO software in the analysis of the variables labeling index and optical density. Spearman's correlation coefficient was estimated in order to evaluate the association between the expression levels of the markers. For the comparison of lesion types, Student's paired t-test and the nonparametric Wilcoxon test were used.

RESULTS

Of the 34 blocks referred for the study of the tumor markers, 15 were positive for Ki-67, 34 showed CD34 expression, and 14 were positive for both markers. The median value for the labeling index of CD34 was 72.72%; the minimum was 5.14% and the maximum, 88.81%. The median for the Ki-67 labeling index was 73.78%, while the minimum was 16.87%, and the maximum, 87.47%. The median value for the optical density of CD34 was 48.33, the minimum was 35.65 and the maximum, 85.86. For the optical density of Ki-67, the median was 40.03, while the minimum and maximum values were 21.53 and 52.43, respectively.

CONCLUSION

The cytophotometric expression of Ki-67 had a mean labeling index of 64.04%, and the mean CD34 labeling index was 61.64%. The cytophotometric expression of the mean optical density of Ki-67 was 39.49, while for CD34 it was 53.69. There was a significant difference between Ki-67 and CD34 immunostaining with respect to optical density (P=0.025); no significant difference occurred regarding labeling index (P=0.470).