Proliferating cell nuclear antigen (PCNA) expression in patients with breast carcinoma in comparison to patients with benign breast diseases.

The proliferating cell nuclear antigen (PCNA) was studied by immunohistochemistry on FNA specimens of 20 breast (ductal) carcinomas, 20 fibroadenomas and 20 atypical fibrocystic lesions of the breast. Sixteen cases of breast carcinomas, eight fibroadenomas but no atypical fibrocystic lesions were found to display nuclear PCNA staining. A significant difference was found, between PCNA index of breast carcinomas (mean PCNA index 56%) and fibroadenomas (mean PCNA 21, 25%). This suggests that breast carcinomas display a higher proliferation index than fibroadenomas and fibrocystic disease. Furthermore, we found variations in PCNA among individual cases of breast carcinomas. This suggests that PCNA index can help in the individual approach of the proliferation rate of each tumour, a parameter of potentially importance for predicting the biological behaviour of the tumour in association with other proliferation markers.