The expression of HLA class I antigen in prostate cancer in relation to tumor differentiation and patient survival.

The expression of HLA class I antigens was studied using the immunoperoxidase technique on 30 patients with prostate cancer and 29 patients with benign prostatic hypertrophy (BPH). Forty-three percent of the tumors stained positive, in contrast to 21% of the BPH. An inverse relationship was noted between class I expression and degree of tumor differentiation: 88% of the well-differentiated tumors (8/9) expressed class I antigen, compared with 33% (3/9) of the moderately differentiated and 16% (2/12) of the poorly differentiated tumors. No significant survival difference was found between those with class I-positive and -negative tumors. However, when both class I expression and degree of differentiation were considered, those with positive tumors at each level of differentiation had better survival than those with negative tumors. These data suggest that HLA class I expression may serve as a finite prognostic factor and may have relevance in future immunotherapy.