The prognostic value of the HNK-1 (Leu-7) antigen in prostatic cancer--an immunohistochemical study.

The anti-HNK-1 (Leu-7) monoclonal antibody (MAb) was revealed to be reactive with noncancerous and cancerous prostatic epithelial cells, although this antibody was originally found to be reactive against natural killer cells. However, the prognostic significance of HNK-1 antigen in prostatic cancer patients remains unknown. The expression of HNK-1 antigen on prostatic cancer was investigated immunohistochemically using the avidin-biotin-peroxidase complex (ABC) method with the anti-HNK-1 monoclonal antibody. Of the 52 patients with prostatic cancer, 49 patients (94%) showed reactivity to anti-HNK-1 MAb and the immunoreaction was associated with the histological differentiation of prostatic cancer. Well differentiated cancer showed the highest percentage of positively stained cancer cells and poorly differentiated cancer showed the lowest percentage. No statistically significant differences existed between groups classified by stage, although the more advanced cancers tended to have weaker reactions. The five-year survival rate and interval free of progression were then studied using the Kaplan-Meier method on 33 patients with stage D2 disease who had received endocrine therapy. The findings indicated that a high survival rate and a longer interval free of progression were associated with a higher fraction of positively stained cancer cells. In conclusion, the expression of HNK-1 antigen on prostatic cancer may be a useful prognostic factor in patients with prostatic cancer.