The identification of 'casein' in human breast cancer.

A retrospective study of ninety-six cases of breast cancer was carried out to determine the prognostic values of a casein immunolocalization technique. This was performed using an indirect immunofluorescence method with antisera raised in rabbits to pooled human casein. Fluorescence positivity was graded according to its intensity and distribution. The pathology of each tumour was studied and the tumour type, histological grade and tissue response assessed. The relationship between these observations and the casein content of the tumour was studied. In addition the correlation between casein content and age, menopausal state, clinical staging and survival was investigated. The incidence of casein positivity in our series was 50% with approximately half of the positive cases showing strong fluorescence. There was a relationship between casein content and the age of the patients, with casein being more frequently found in tumours from younger patients. Tumours with a high casein content, in general, show a poorer survival than the group as a whole. This difference in survival was most marked in the first eight years after operation and restricted to those tumours in clinical stage I and histological grade I. The presence of casein in the tumours did not appear to be related to the other factors examined.