Clinical trials of immunotherapy in patients with breast cancer have been limited. Although immune function does not appear to be depressed in patients with operable breast cancer, immune function may play a role in preventing tumour recurrence in such patients. For example, 2 features associated with an adverse prognosis include peripheral blood lymphocytopenia and lack of reactivity against autologous tumour in skin windows.
A number of agents that specifically or nonspecifically augment immunity have been studied. These include levamisole, the interferons, interleukin-2, cyclosporin, tumour vaccines, monoclonal antibodies and immunotoxins. Most of these trials have involved treatment of patients with advanced disease, and little antineoplastic activity has been demonstrated in this setting. Randomised trials have found no proven benefit for treatment with interferon-α or levamisole in addition to standard chemotherapy in patients with breast cancer, although these agents may not have been used optimally in these studies.
Improved understanding of the biology of breast cancer is likely to result in more rationally designed biological therapies employing entirely new treatment strategies, or using currently available drugs more effectively. Furthermore, levamisole combined with fluorouracil in patients with Duke's C colon cancer can result in an improved outcome when compared with fluorouracil alone. This suggests that carcinomas of glandular origin may be immunologically responsive, and that it may be possible to produce clinical benefit with immunological therapies even if the precise basis for the benefit has not been defined.