The Immunology of Breast Cancer

Abstract

Adenocarcinoma of the breast is a major cancer of women. Evidence indicates that breast cancers may be latent for long periods, perhaps as a result of host response. Based upon an extensive review of the available literature, it appears that breast cancers are immunogenic and that host reactions to the antigens involved determine prognosis. Breast cancers generally show lymphocyte infiltration. These tumour-associated lymphocytes correlate with prognosis when histological grade and clinical stage are controlled for as variables. The interpretation of secondary changes in regional lymph nodes is controversial. The data indicate prognostically significant reactions reflecting immunity. Tumour-associated lymphocytes from tumour and regional nodes are T lymphocytes that are suppressed in their function, presumably by factors derived from both the patients’ tumour and tumour-immune cell interaction. However, when they are grown in interleukin-2 they can show a high degree of antitumour reactivity. Studies of patients’ immune competence show progressive cellular immune deficiency which correlates with prognosis. A variety of human studies in vitro and in vivo show both cellular and humoral immune reactions to tumour-associated antigens. Tumour markers and antigens include HER-2/neu, P53, mucin carbohydrates and peptides, mouse mammary tumour virus-related peptides and other less well characterised antigens. Murine models for breast cancer show a similar immunological picture and provide a proving ground for testing immunotherapeutics. Early immunotherapy of breast cancer in humans was not successful; however, recent efforts using combinations involving tumour vaccines, adjuvants, contrasuppression, thymic hormones and natural interleukins are encouraging.