Strong HLA-DR expression in large bowel carcinomas is associated with good prognosis.

One hundred large bowel carcinomas operated on between 1978 and 1982 were studied immunohistochemically with regard to expression of HLA-DR antigens. Three sections from each tumour were investigated by a semiquantitative scoring system, and a mean score for each patient established. Based on this scoring system, the tumours were divided into three groups: 0; 0.1-1.0; and > 1.0. All patients were followed until death (n = 68) or until June 1, 1992, and all cancer-specific deaths (n = 56) have been recorded. Analysis of survival in the whole patient group showed significant difference between the three levels of tumour HLA-DR expression (P = 0.006); patients who had tumours with strong HLA-DR expression showing the best survival. In a stratified analysis after Dukes' stages there was still a significant difference (P > 0.001) between the three levels of HLA-DR staining intensity. After a multiple regression analysis (Cox) with correction for different variables, the HLA-DR expression maintained its significance as a risk factor. To our knowledge this is the first time a relationship between intensity of tumour DR expression and survival has been shown in large bowel carcinoma.