The role of biological response modifiers in the management of patients with colorectal cancer.

Biological response modifiers are agents which exert their antitumour effects indirectly via modulation of the host's response to the tumour. Immunotherapeutic approaches which fall into this category can be divided into specific and non-specific. An example of the latter is the combination of 5-fluorouracil (5-FU) with levamisole which improves survival of patients with colorectal carcinoma when utilised in an adjuvant setting. Specific immunotherapy using active specific immunisation is attracting much attention. This is in part due to improvements in survival seen in one randomised clinical trial in an adjuvant setting, and also to exciting advances in the fields of tumour immunity and vaccine development. The development of more effective vaccines promises much for patients with early colorectal carcinomas.